draft-ietf-netmod-artwork-folding-12.txt		rfc8792.txt
	NETMOD Working Group K. Watsen		Internet Engineering Task Force (IETF) K. Watsen
	Internet-Draft Watsen Networks		Request for Comments: 8792 Watsen Networks
	Intended status: Informational E. Auerswald		Category: Informational E. Auerswald
	Expires: July 23, 2020 Individual Contributor		ISSN: 2070-1721 Individual Contributor
	A. Farrel		A. Farrel
	Old Dog Consulting		Old Dog Consulting
	Q. Wu		Q. Wu
	Huawei Technologies		Huawei Technologies
	January 20, 2020		June 2020
	Handling Long Lines in Inclusions in Internet-Drafts and RFCs		Handling Long Lines in Content of Internet-Drafts and RFCs
	draft-ietf-netmod-artwork-folding-12
	Abstract		Abstract
	This document defines two strategies for handling long lines in		This document defines two strategies for handling long lines in
	width-bounded text content. One strategy is based on the historical		width-bounded text content. One strategy, called the "single
	use of a single backslash ('\') character to indicate where line-		backslash" strategy, is based on the historical use of a single
	folding has occurred, with the continuation occurring with the first		backslash ('\') character to indicate where line-folding has
	non-space (' ') character on the next line. The second strategy		occurred, with the continuation occurring with the first character
	extends the first strategy by adding a second backslash character to		that is not a space character (' ') on the next line. The second
	identify where the continuation begins and is thereby able to handle		strategy, called the "double backslash" strategy, extends the first
	cases not supported by the first strategy. Both strategies use a		strategy by adding a second backslash character to identify where the
	self-describing header enabling automated reconstitution of the		continuation begins and is thereby able to handle cases not supported
	original content.		by the first strategy. Both strategies use a self-describing header
			enabling automated reconstitution of the original content.
	Editorial Note (To be removed by RFC Editor)
	Please be aware that this document uses throughout the five-character
	text sequence located between the following two double-quotes: "('
	')". It has been observed that some renderings of this text sequence
	produces a natural line break at the space character in the middle,
	thus causing "('" to appear at the end of the first line and "')" to
	appear at the beginning of the next line. Such a line-break is
	confusing and should not occur in the RFC output formats.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This document is not an Internet Standards Track specification; it is
	provisions of BCP 78 and BCP 79.		published for informational purposes.
	Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		This document is a product of the Internet Engineering Task Force
	and may be updated, replaced, or obsoleted by other documents at any		(IETF). It represents the consensus of the IETF community. It has
	time. It is inappropriate to use Internet-Drafts as reference		received public review and has been approved for publication by the
	material or to cite them other than as "work in progress."		Internet Engineering Steering Group (IESG). Not all documents
			approved by the IESG are candidates for any level of Internet
			Standard; see Section 2 of RFC 7841.
	This Internet-Draft will expire on July 23, 2020.		Information about the current status of this document, any errata,
			and how to provide feedback on it may be obtained at
			https://www.rfc-editor.org/info/rfc8792.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	described in the Simplified BSD License.		described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction
	2. Applicability Statement . . . . . . . . . . . . . . . . . . . 4		2. Applicability Statement
	3. Requirements Language . . . . . . . . . . . . . . . . . . . . 4		3. Requirements Language
	4. Goals . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4		4. Goals
	4.1. Automated Folding of Long Lines in Text Content . . . . . 4		4.1. Automated Folding of Long Lines in Text Content
	4.2. Automated Reconstitution of the Original Text Content . . 5		4.2. Automated Reconstitution of the Original Text Content
	5. Limitations . . . . . . . . . . . . . . . . . . . . . . . . . 5		5. Limitations
	5.1. Not Recommended for Graphical Artwork . . . . . . . . . . 5		5.1. Not Recommended for Graphical Artwork
	5.2. Doesn't Work as Well as Format-Specific Options . . . . . 6		5.2. Doesn't Work as Well as Format-Specific Options
	6. Two Folding Strategies . . . . . . . . . . . . . . . . . . . 6		6. Two Folding Strategies
	6.1. Comparison . . . . . . . . . . . . . . . . . . . . . . . 6		6.1. Comparison
	6.2. Recommendation . . . . . . . . . . . . . . . . . . . . . 7		6.2. Recommendation
	7. The Single Backslash Strategy ('\') . . . . . . . . . . . . . 7		7. The Single Backslash Strategy ('\')
	7.1. Folded Structure . . . . . . . . . . . . . . . . . . . . 7		7.1. Folded Structure
	7.1.1. Header . . . . . . . . . . . . . . . . . . . . . . . 7		7.1.1. Header
	7.1.2. Body . . . . . . . . . . . . . . . . . . . . . . . . 7		7.1.2. Body
	7.2. Algorithm . . . . . . . . . . . . . . . . . . . . . . . . 7		7.2. Algorithm
	7.2.1. Folding . . . . . . . . . . . . . . . . . . . . . . . 8		7.2.1. Folding
	7.2.2. Unfolding . . . . . . . . . . . . . . . . . . . . . . 9		7.2.2. Unfolding
	8. The Double Backslash Strategy ('\\') . . . . . . . . . . . . 10		8. The Double Backslash Strategy ('\\')
	8.1. Folded Structure . . . . . . . . . . . . . . . . . . . . 10		8.1. Folded Structure
	8.1.1. Header . . . . . . . . . . . . . . . . . . . . . . . 10		8.1.1. Header
	8.1.2. Body . . . . . . . . . . . . . . . . . . . . . . . . 10		8.1.2. Body
	8.2. Algorithm . . . . . . . . . . . . . . . . . . . . . . . . 10		8.2. Algorithm
	8.2.1. Folding . . . . . . . . . . . . . . . . . . . . . . . 11		8.2.1. Folding
	8.2.2. Unfolding . . . . . . . . . . . . . . . . . . . . . . 12		8.2.2. Unfolding
	9. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 12		9. Examples
	9.1. Example Showing Boundary Conditions . . . . . . . . . . . 13		9.1. Example Showing Boundary Conditions
	9.1.1. Using '\' . . . . . . . . . . . . . . . . . . . . . . 13		9.1.1. Using '\'
	9.1.2. Using '\\' . . . . . . . . . . . . . . . . . . . . . 13		9.1.2. Using '\\'
	9.2. Example Showing Multiple Wraps of a Single Line . . . . . 13		9.2. Example Showing Multiple Wraps of a Single Line
	9.2.1. Using '\' . . . . . . . . . . . . . . . . . . . . . . 14		9.2.1. Using '\'
	9.2.2. Using '\\' . . . . . . . . . . . . . . . . . . . . . 14		9.2.2. Using '\\'
	9.3. Example Showing "Smart" Folding . . . . . . . . . . . . . 14		9.3. Example Showing "Smart" Folding
	9.3.1. Using '\' . . . . . . . . . . . . . . . . . . . . . . 14		9.3.1. Using '\'
	9.3.2. Using '\\' . . . . . . . . . . . . . . . . . . . . . 15		9.3.2. Using '\\'
	9.4. Example Showing "Forced" Folding . . . . . . . . . . . . 16		9.4. Example Showing "Forced" Folding
	9.4.1. Using '\' . . . . . . . . . . . . . . . . . . . . . . 17		9.4.1. Using '\'
	9.4.2. Using '\\' . . . . . . . . . . . . . . . . . . . . . 17		9.4.2. Using '\\'
	10. Security Considerations . . . . . . . . . . . . . . . . . . . 18		10. Security Considerations
	11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18		11. IANA Considerations
	12. References . . . . . . . . . . . . . . . . . . . . . . . . . 18		12. References
	12.1. Normative References . . . . . . . . . . . . . . . . . . 18		12.1. Normative References
	12.2. Informative References . . . . . . . . . . . . . . . . . 19		12.2. Informative References
	Appendix A. Bash Shell Script: rfcfold . . . . . . . . . . . . . 20		Appendix A. Bash Shell Script: rfcfold
	Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 30		Acknowledgements
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 30		Authors' Addresses
	1. Introduction		1. Introduction
	[RFC7994] sets out the requirements for plain-text RFCs and states		[RFC7994] sets out the requirements for plain-text RFCs and states
	that each line of an RFC (and hence of an Internet-Draft) must be		that each line of an RFC (and hence of an Internet-Draft) must be
	limited to 72 characters followed by the character sequence that		limited to 72 characters followed by the character sequence that
	denotes an end-of-line (EOL).		denotes an end-of-line (EOL).
	Internet-Drafts and RFCs often include example text or code		Internet-Drafts and RFCs often include example text or code
	fragments. Many times the example text or code exceeds the 72		fragments. Many times, the example text or code exceeds the
	character line-length limit. The `xml2rfc` [xml2rfc] utility, at the		72-character line-length limit. The 'xml2rfc' utility [xml2rfc], at
	time of this document's publication, does not attempt to wrap the		the time of this document's publication, does not attempt to wrap the
	content of such inclusions, simply issuing a warning whenever lines		content of such inclusions, simply issuing a warning whenever lines
	exceed 69 characters. Historically, there has been no RFC-Editor-		exceed 69 characters. Historically, there has been no convention
	recommended convention in place for how to handle long lines in such		recommended by the RFC Editor in place for how to handle long lines
	inclusions, other than advising authors to clearly indicate what		in such inclusions, other than advising authors to clearly indicate
	manipulation has occurred.		what manipulation has occurred.
	This document defines two strategies for handling long lines in		This document defines two strategies for handling long lines in
	width-bounded text content. One strategy is based on the historical		width-bounded text content. One strategy, called the "single
	use of a single backslash ('\') character to indicate where line-		backslash" strategy, is based on the historical use of a single
	folding has occurred, with the continuation occurring with the first		backslash ('\') character to indicate where line-folding has
	non-space (' ') character on the next line. The second strategy		occurred, with the continuation occurring with the first character
	extends the first strategy by adding a second backslash character to		that is not a space character (' ') on the next line. The second
	identify where the continuation begins and is thereby able to handle		strategy, called the "double backslash" strategy, extends the first
	cases not supported by the first strategy. Both strategies use a		strategy by adding a second backslash character to identify where the
	self-describing header enabling automated reconstitution of the		continuation begins and is thereby able to handle cases not supported
	original content.		by the first strategy. Both strategies use a self-describing header
			enabling automated reconstitution of the original content.
	The strategies defined in this document work on any text content, but		The strategies defined in this document work on any text content but
	are primarily intended for a structured sequence of lines, such as		are primarily intended for a structured sequence of lines, such as
	would be referenced by the <sourcecode> element defined in		would be referenced by the <sourcecode> element defined in
	Section 2.48 of [RFC7991], rather than for two-dimensional imagery,		Section 2.48 of [RFC7991], rather than for two-dimensional imagery,
	such as would be referenced by the <artwork> element defined in		such as would be referenced by the <artwork> element defined in
	Section 2.5 of [RFC7991].		Section 2.5 of [RFC7991].
	Note that text files are represented as lines having their first		Note that text files are represented as lines having their first
	character in column 1, and a line length of N where the last		character in column 1, and a line length of N where the last
	character is in the Nth column and is immediately followed by an end		character is in the Nth column and is immediately followed by an end-
	of line character sequence.		of-line character sequence.
	2. Applicability Statement		2. Applicability Statement
	The formats and algorithms defined in this document may be used in		The formats and algorithms defined in this document may be used in
	any context, whether for IETF documents or in other situations where		any context, whether for IETF documents or in other situations where
	structured folding is desired.		structured folding is desired.
	Within the IETF, this work primarily targets the xml2rfc v3		Within the IETF, this work primarily targets the xml2rfc v3
	<sourcecode> element (Section 2.48 of [RFC7991]) and the xml2rfc v2		<sourcecode> element (Section 2.48 of [RFC7991]) and the xml2rfc v2
	<artwork> element (Section 2.5 of [RFC7749]) that, for lack of a		<artwork> element (Section 2.5 of [RFC7749]), which, for lack of a
	better option, is currently used for both source code and artwork.		better option, is used in xml2rfc v2 for both source code and
	This work may also be used for the xml2rfc v3 <artwork> element		artwork. This work may also be used for the xml2rfc v3 <artwork>
	(Section 2.5 of [RFC7991]) but, as described in Section 5.1, it is		element (Section 2.5 of [RFC7991]), but as described in Section 5.1,
	generally not recommended.		it is generally not recommended.
	3. Requirements Language		3. Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	4. Goals		4. Goals
	4.1. Automated Folding of Long Lines in Text Content		4.1. Automated Folding of Long Lines in Text Content
	Automated folding of long lines is needed in order to support drafts		Automated folding of long lines is needed in order to support
	that are dynamically compiled to include content with potentially		documents that are dynamically compiled to include content with
	unconstrained line lengths. For instance, the build process may wish		potentially unconstrained line lengths. For instance, the build
	to include content from other local files or dynamically generated by		process may wish to include content from other local files or content
	some external process. Both of these cases are discussed next.		that is dynamically generated by some external process. Both of
			these cases are discussed next.
	Many drafts need to include the content from local files (e.g., XML,		Many documents need to include the content from local files (e.g.,
	JSON, ABNF, ASN.1). Prior to including a file's content, the build		XML, JSON, ABNF, ASN.1). Prior to including a file's content, the
	process SHOULD first validate these source files using format-		build process SHOULD first validate these source files using format-
	specific validators. In order for such tooling to be able to process		specific validators. In order for such tooling to be able to process
	the files, the files must be in their original/natural state, which		the files, the files must be in their original/natural state, which
	may entail them having some long lines. Thus, these source files		may entail them having some long lines. Thus, these source files
	need to be folded before inclusion into the XML document, in order to		need to be folded before inclusion into the XML document, in order to
	satisfy `xml2rfc` line length limits.		satisfy 'xml2rfc' line-length limits.
	Similarly, drafts sometimes contain dynamically generated output,		Similarly, documents sometimes contain dynamically generated output,
	typically from an external process operating on the same source files		typically from an external process operating on the same source files
	discussed in the previous paragraph. For instance, such processes		discussed in the previous paragraph. For instance, such processes
	may translate the input format to another format or render a report		may translate the input format to another format, or they may render
	over or a view of the input file. In some cases, the dynamically		a report on, or a view of, the input file. In some cases, the
	generated output may contain lines exceeding the `xml2rfc` line		dynamically generated output may contain lines exceeding the
	length limits.		'xml2rfc' line-length limits.
	In both cases, folding is required and SHOULD be automated to reduce		In both cases, folding is required and SHOULD be automated to reduce
	effort and errors resulting from manual processing.		effort and errors resulting from manual processing.
	4.2. Automated Reconstitution of the Original Text Content		4.2. Automated Reconstitution of the Original Text Content
	Automated reconstitution of the exact original text content is needed		Automated reconstitution of the exact original text content is needed
	to support validation of text-based content extracted from documents.		to support validation of text-based content extracted from documents.
	For instance, already YANG [RFC7950] modules are extracted from		For instance, YANG modules [RFC7950] are already extracted from
	Internet-Drafts and validated as part of the draft-submission		Internet-Drafts and validated as part of the submission process.
	process. Additionally, the desire to validate instance examples		Additionally, the desire to validate instance examples (i.e., XML/
	(i.e., XML/JSON documents) contained within Internet-Drafts has been		JSON documents) contained within Internet-Drafts has been discussed
	discussed ([yang-doctors-thread]).		[yang-doctors-thread].
	5. Limitations		5. Limitations
	5.1. Not Recommended for Graphical Artwork		5.1. Not Recommended for Graphical Artwork
	While the solution presented in this document works on any kind of		While the solution presented in this document works on any kind of
	text-based content, it is most useful on content that represents		text-based content, it is most useful on content that represents
	source code (XML, JSON, etc.) or, more generally, on content that has		source code (XML, JSON, etc.) or, more generally, on content that has
	not been laid out in two dimensions (e.g., diagrams).		not been laid out in two dimensions (e.g., diagrams).
	Fundamentally, the issue is whether the text content remains readable		Fundamentally, the issue is whether the text content remains readable
	once folded. Text content that is unpredictable is especially		once folded. Text content that is unpredictable is especially
	susceptible to looking bad when folded; falling into this category		susceptible to looking bad when folded; falling into this category
	are most UML diagrams, YANG tree diagrams, and ASCII art in general.		are most Unified Modeling Language (UML) diagrams, YANG tree
			diagrams, and ASCII art in general.
	It is NOT RECOMMENDED to use the solution presented in this document		It is NOT RECOMMENDED to use the solution presented in this document
	on graphical artwork.		on graphical artwork.
	5.2. Doesn't Work as Well as Format-Specific Options		5.2. Doesn't Work as Well as Format-Specific Options
	The solution presented in this document works generically for all		The solution presented in this document works generically for all
	text-based content, as it only views content as plain text. However,		text-based content, as it only views content as plain text. However,
	various formats sometimes have built-in mechanisms that are better		various formats sometimes have built-in mechanisms that are better
	suited to prevent long lines.		suited to prevent long lines.
	For instance, both the `pyang` [pyang] and `yanglint` [yanglint]		For instance, both the 'pyang' and 'yanglint' utilities [pyang]
	utilities have the command line option "--tree-line-length" that can		[yanglint] have the command-line option "tree-line-length", which can
	be used to indicate a desired maximum line length for when generating		be used to indicate a desired maximum line length when generating
	tree diagrams [RFC8340].		YANG tree diagrams [RFC8340].
	In another example, some source formats (e.g., YANG [RFC7950]) allow		In another example, some source formats (e.g., YANG [RFC7950]) allow
	any quoted string to be broken up into substrings separated by a		any quoted string to be broken up into substrings separated by a
	concatenation character (e.g., '+'), any of which can be on a		concatenation character (e.g., '+'), any of which can be on a
	different line.		different line.
	It is RECOMMENDED that authors do as much as possible within the		It is RECOMMENDED that authors do as much as possible within the
	selected format to avoid long lines.		selected format to avoid long lines.
	6. Two Folding Strategies		6. Two Folding Strategies
	This document defines two nearly identical strategies for folding		This document defines two nearly identical strategies for folding
	text-based content.		text-based content.
	The Single Backslash Strategy ('\'): Uses a backslash ('\')		The Single Backslash Strategy ('\'):
	character at the end of the line where folding occurs, and		Uses a backslash ('\') character at the end of the line where
	assumes that the continuation begins at the first character		folding occurs, and assumes that the continuation begins at the
	that is not a space character (' ') on the following line.		first character that is not a space character (' ') on the
			following line.
	The Double Backslash Strategy ('\\'): Uses a backslash ('\')		The Double Backslash Strategy ('\\'):
	character at the end of the line where folding occurs, and		Uses a backslash ('\') character at the end of the line where
	assumes that the continuation begins after a second backslash		folding occurs, and assumes that the continuation begins after a
	('\') character on the following line.		second backslash ('\') character on the following line.
	6.1. Comparison		6.1. Comparison
	The first strategy produces more readable output, however it is		The first strategy produces output that is more readable. However,
	significantly more likely to encounter unfoldable input (e.g., a long		(1) it is significantly more likely to encounter unfoldable input
	line containing only space characters) and, for long lines that can		(e.g., a long line containing only space characters), and (2) for
	be folded, automation implementations may encounter scenarios that		long lines that can be folded, automation implementations may
	will produce errors without special care.		encounter scenarios that, without special care, will produce errors.
	The second strategy produces less readable output, but is unlikely to		The second strategy produces output that is less readable, but it is
	encounter unfoldable input, there are no long lines that cannot be		unlikely to encounter unfoldable input, there are no long lines that
	folded, and no special care is required for when folding a long line.		cannot be folded, and no special care is required when folding a long
			line.
	6.2. Recommendation		6.2. Recommendation
	It is RECOMMENDED for implementations to first attempt to fold		It is RECOMMENDED that implementations first attempt to fold content
	content using the single backslash strategy and, only in the unlikely		using the single backslash strategy and, only in the unlikely event
	event that it cannot fold the input or the folding logic is unable to		that it cannot fold the input or the folding logic is unable to cope
	cope with a contingency occurring on the desired folding column, then		with a contingency occurring on the desired folding column, then fall
	fallback to the double backslash strategy.		back to the double backslash strategy.
	7. The Single Backslash Strategy ('\')		7. The Single Backslash Strategy ('\')
	7.1. Folded Structure		7.1. Folded Structure
	Text content that has been folded as specified by this strategy MUST		Text content that has been folded as specified by this strategy MUST
	adhere to the following structure.		adhere to the following structure.
	7.1.1. Header		7.1.1. Header
	The header is two lines long.		The header is two lines long.
	The first line is the following 46-character string that MAY be		The first line is the following 36-character string; this string MAY
	surrounded by any number of printable characters. This first line		be surrounded by any number of printable characters. This first line
	cannot itself be folded.		cannot itself be folded.
	NOTE: '\' line wrapping per BCP XXX (RFC XXXX)		NOTE: '\' line wrapping per RFC 8792
	[Note to RFC Editor: Please replace XXX and XXXX with the numbers
	assigned to this document and delete this note. Please make this
	change in multiple places in this document.]
	The second line is an empty line, containing only the end-of-line		The second line is an empty line, containing only the end-of-line
	character sequence. This line provides visual separation for		character sequence. This line provides visual separation for
	readability.		readability.
	7.1.2. Body		7.1.2. Body
	The character encoding is the same as described in Section 2 of		The character encoding is the same as the encoding described in
	[RFC7994], except that, per [RFC7991], tab characters are prohibited.		Section 2 of [RFC7994], except that, per [RFC7991], tab characters
			are prohibited.
	Lines that have a backslash ('\') occurring as the last character in		Lines that have a backslash ('\') occurring as the last character in
	a line are considered "folded".		a line are considered "folded".
	Exceptionally long lines may be folded multiple times.		Exceptionally long lines MAY be folded multiple times.
	7.2. Algorithm		7.2. Algorithm
	This section describes a process for folding and unfolding long lines		This section describes a process for folding and unfolding long lines
	when they are encountered in text content.		when they are encountered in text content.
	The steps are complete, but implementations MAY achieve the same		The steps are complete, but implementations MAY achieve the same
	result in other ways.		result in other ways.
	When a larger document contains multiple instances of text content		When a larger document contains multiple instances of text content
	that may need to be folded or unfolded, another process must insert/		that may need to be folded or unfolded, another process must
	extract the individual text content instances to/from the larger		insert/extract the individual text content instances to/from the
	document prior to utilizing the algorithms described in this section.		larger document prior to utilizing the algorithms described in this
	For example, the `xiax` utility [xiax] does this.		section. For example, the 'xiax' utility [xiax] does this.
	7.2.1. Folding		7.2.1. Folding
	Determine the desired maximum line length from input to the line-		Determine the desired maximum line length from input to the line-
	wrapping process, such as from a command line parameter. If no value		wrapping process, such as from a command-line parameter. If no value
	is explicitly specified, the value "69" SHOULD be used.		is explicitly specified, the value "69" SHOULD be used.
	Ensure that the desired maximum line length is not less than the		Ensure that the desired maximum line length is not less than the
	minimum header, which is 46 characters. If the desired maximum line		minimum header, which is 36 characters. If the desired maximum line
	length is less than this minimum, exit (this text-based content		length is less than this minimum, exit (this text-based content
	cannot be folded).		cannot be folded).
	Scan the text content for horizontal tab characters. If any		Scan the text content for horizontal tab characters. If any
	horizontal tab characters appear, either resolve them to space		horizontal tab characters appear, either resolve them to space
	characters or exit, forcing the input provider to convert them to		characters or exit, forcing the input provider to convert them to
	space characters themselves first.		space characters themselves first.
	Scan the text content to ensure at least one line exceeds the desired		Scan the text content to ensure that at least one line exceeds the
	maximum. If no line exceeds the desired maximum, exit (this text		desired maximum. If no line exceeds the desired maximum, exit (this
	content does not need to be folded).		text content does not need to be folded).
	Scan the text content to ensure no existing lines already end with a		Scan the text content to ensure that no existing lines already end
	backslash ('\') character, as this could lead to an ambiguous result.		with a backslash ('\') character, as this could lead to an ambiguous
	If such a line is found, and its width is less than the desired		result. If such a line is found, and its width is less than the
	maximum, then it SHOULD be flagged for forced folding (folding even		desired maximum, then it SHOULD be flagged for "forced" folding
	though unnecessary). If the folding implementation doesn't support		(folding even though unnecessary). If the folding implementation
	forced foldings, it MUST exit.		doesn't support forced foldings, it MUST exit.
	If this text content needs to and can be folded, insert the header		If this text content needs to, and can, be folded, insert the header
	described in Section 7.1.1, ensuring that any additional printable		described in Section 7.1.1, ensuring that any additional printable
	characters surrounding the header do not result in a line exceeding		characters surrounding the header do not result in a line exceeding
	the desired maximum.		the desired maximum.
	For each line in the text content, from top-to-bottom, if the line		For each line in the text content, from top to bottom, if the line
	exceeds the desired maximum, or requires a forced folding, then fold		exceeds the desired maximum or requires a forced folding, then fold
	the line by:		the line by performing the following steps:
	1. Determine where the fold will occur. This location MUST be		1. Determine where the fold will occur. This location MUST be
	before or at the desired maximum column, and MUST NOT be chosen		before or at the desired maximum column and MUST NOT be chosen
	such that the character immediately after the fold is a space ('		such that the character immediately after the fold is a space
	') character. For forced foldings, the location is between the		(' ') character. For forced foldings, the location is between
	'\' and the end of line sequence. If no such location can be		the '\' and the end-of-line sequence. If no such location can be
	found, then exit (this text content cannot be folded).		found, then exit (this text content cannot be folded).
	2. At the location where the fold is to occur, insert a backslash		2. At the location where the fold is to occur, insert a backslash
	('\') character followed by the end of line character sequence.		('\') character followed by the end-of-line character sequence.
	3. On the following line, insert any number of space (' ')		3. On the following line, insert any number of space (' ')
	characters, subject to the resulting line not exceeding the		characters, provided that the resulting line does not exceed the
	desired maximum.		desired maximum.
	The result of the previous operation is that the next line starts		The result of the previous operation is that the next line starts
	with an arbitrary number of space (' ') characters, followed by the		with an arbitrary number of space (' ') characters, followed by the
	character that was previously occupying the position where the fold		character that was previously occupying the position where the fold
	occurred.		occurred.
	Continue in this manner until reaching the end of the text content.		Continue in this manner until reaching the end of the text content.
	Note that this algorithm naturally addresses the case where the		Note that this algorithm naturally addresses the case where the
	remainder of a folded line is still longer than the desired maximum,		remainder of a folded line is still longer than the desired maximum
	and hence needs to be folded again, ad infinitum.		and, hence, needs to be folded again, ad infinitum.
	The process described in this section is illustrated by the		The process described in this section is illustrated by the
	"fold_it_1()" function in Appendix A.		"fold_it_1()" function in Appendix A.
	7.2.2. Unfolding		7.2.2. Unfolding
	Scan the beginning of the text content for the header described in		Scan the beginning of the text content for the header described in
	Section 7.1.1. If the header is not present, exit (this text content		Section 7.1.1. If the header is not present, exit (this text content
	does not need to be unfolded).		does not need to be unfolded).
	Remove the 2-line header from the text content.		Remove the two-line header from the text content.
	For each line in the text content, from top-to-bottom, if the line		For each line in the text content, from top to bottom, if the line
	has a backslash ('\') character immediately followed by the end of		has a backslash ('\') character immediately followed by the end-of-
	line character sequence, then the line can be unfolded. Remove the		line character sequence, then the line can be unfolded. Remove the
	backslash ('\') character, the end of line character sequence, and		backslash ('\') character, the end-of-line character sequence, and
	any leading space (' ') characters, which will bring up the next		any leading space (' ') characters, which will bring up the next
	line. Then continue to scan each line in the text content starting		line. Then continue to scan each line in the text content starting
	with the current line (in case it was multiply folded).		with the current line (in case it was multiply folded).
	Continue in this manner until reaching the end of the text content.		Continue in this manner until reaching the end of the text content.
	The process described in this section is illustrated by the		The process described in this section is illustrated by the
	"unfold_it_1()" function in Appendix A.		"unfold_it_1()" function in Appendix A.
	8. The Double Backslash Strategy ('\\')		8. The Double Backslash Strategy ('\\')
	8.1. Folded Structure		8.1. Folded Structure
	Text content that has been folded as specified by this strategy MUST		Text content that has been folded as specified by this strategy MUST
	adhere to the following structure.		adhere to the following structure.
	8.1.1. Header		8.1.1. Header
	The header is two lines long.		The header is two lines long.
	The first line is the following 47-character string that MAY be		The first line is the following 37-character string; this string MAY
	surrounded by any number of printable characters. This first line		be surrounded by any number of printable characters. This first line
	cannot itself be folded.		cannot itself be folded.
	NOTE: '\\' line wrapping per BCP XXX (RFC XXXX)		NOTE: '\\' line wrapping per RFC 8792
	[Note to RFC Editor: Please replace XXX and XXXX with the numbers
	assigned to this document and delete this note. Please make this
	change in multiple places in this document.]
	The second line is an empty line, containing only the end-of-line		The second line is an empty line, containing only the end-of-line
	character sequence. This line provides visual separation for		character sequence. This line provides visual separation for
	readability.		readability.
	8.1.2. Body		8.1.2. Body
	The character encoding is the same as described in Section 2 of		The character encoding is the same as the encoding described in
	[RFC7994], except that, per [RFC7991], tab characters are prohibited.		Section 2 of [RFC7994], except that, per [RFC7991], tab characters
			are prohibited.
	Lines that have a backslash ('\') occurring as the last character in		Lines that have a backslash ('\') occurring as the last character in
	a line immediately followed by the end of line character sequence,		a line immediately followed by the end-of-line character sequence,
	when the subsequent line starts with a backslash ('\') as the first		when the subsequent line starts with a backslash ('\') as the first
	non-space (' ') character, are considered "folded".		character that is not a space character (' '), are considered
			"folded".
	Exceptionally long lines may be folded multiple times.		Exceptionally long lines MAY be folded multiple times.
	8.2. Algorithm		8.2. Algorithm
	This section describes a process for folding and unfolding long lines		This section describes a process for folding and unfolding long lines
	when they are encountered in text content.		when they are encountered in text content.
	The steps are complete, but implementations MAY achieve the same		The steps are complete, but implementations MAY achieve the same
	result in other ways.		result in other ways.
	When a larger document contains multiple instances of text content		When a larger document contains multiple instances of text content
	that may need to be folded or unfolded, another process must insert/		that may need to be folded or unfolded, another process must
	extract the individual text content instances to/from the larger		insert/extract the individual text content instances to/from the
	document prior to utilizing the algorithms described in this section.		larger document prior to utilizing the algorithms described in this
	For example, the `xiax` utility [xiax] does this.		section. For example, the 'xiax' utility [xiax] does this.
	8.2.1. Folding		8.2.1. Folding
	Determine the desired maximum line length from input to the line-		Determine the desired maximum line length from input to the line-
	wrapping process, such as from a command line parameter. If no value		wrapping process, such as from a command-line parameter. If no value
	is explicitly specified, the value "69" SHOULD be used.		is explicitly specified, the value "69" SHOULD be used.
	Ensure that the desired maximum line length is not less than the		Ensure that the desired maximum line length is not less than the
	minimum header, which is 47 characters. If the desired maximum line		minimum header, which is 37 characters. If the desired maximum line
	length is less than this minimum, exit (this text-based content		length is less than this minimum, exit (this text-based content
	cannot be folded).		cannot be folded).
	Scan the text content for horizontal tab characters. If any		Scan the text content for horizontal tab characters. If any
	horizontal tab characters appear, either resolve them to space		horizontal tab characters appear, either resolve them to space
	characters or exit, forcing the input provider to convert them to		characters or exit, forcing the input provider to convert them to
	space characters themselves first.		space characters themselves first.
	Scan the text content to see if any line exceeds the desired maximum.		Scan the text content to see if any line exceeds the desired maximum.
	If no line exceeds the desired maximum, exit (this text content does		If no line exceeds the desired maximum, exit (this text content does
	not need to be folded).		not need to be folded).
	Scan the text content to ensure no existing lines already end with a		Scan the text content to ensure that no existing lines already end
	backslash ('\') character while the subsequent line starts with a		with a backslash ('\') character while the subsequent line starts
	backslash ('\') character as the first non-space (' ') character, as		with a backslash ('\') character as the first character that is not a
	this could lead to an ambiguous result. If such a line is found, and		space character (' '), as this could lead to an ambiguous result. If
	its width is less than the desired maximum, then it SHOULD be flagged		such a line is found and its width is less than the desired maximum,
	for forced folding (folding even though unnecessary). If the folding		then it SHOULD be flagged for forced folding (folding even though
	implementation doesn't support forced foldings, it MUST exit.		unnecessary). If the folding implementation doesn't support forced
			foldings, it MUST exit.
	If this text content needs to and can be folded, insert the header		If this text content needs to, and can, be folded, insert the header
	described in Section 8.1.1, ensuring that any additional printable		described in Section 8.1.1, ensuring that any additional printable
	characters surrounding the header do not result in a line exceeding		characters surrounding the header do not result in a line exceeding
	the desired maximum.		the desired maximum.
	For each line in the text content, from top-to-bottom, if the line		For each line in the text content, from top to bottom, if the line
	exceeds the desired maximum, or requires a forced folding, then fold		exceeds the desired maximum or requires a forced folding, then fold
	the line by:		the line by performing the following steps:
	1. Determine where the fold will occur. This location MUST be		1. Determine where the fold will occur. This location MUST be
	before or at the desired maximum column. For forced foldings,		before or at the desired maximum column. For forced foldings,
	the location is between the '\' and the end of line sequence on		the location is between the '\' and the end-of-line sequence on
	the first line.		the first line.
	2. At the location where the fold is to occur, insert a first		2. At the location where the fold is to occur, insert a first
	backslash ('\') character followed by the end of line character		backslash ('\') character followed by the end-of-line character
	sequence.		sequence.
	3. On the following line, insert any number of space (' ')		3. On the following line, insert any number of space (' ')
	characters, subject to the resulting line not exceeding the		characters, provided that the resulting line does not exceed the
	desired maximum, followed by a second backslash ('\') character.		desired maximum, followed by a second backslash ('\') character.
	The result of the previous operation is that the next line starts		The result of the previous operation is that the next line starts
	with an arbitrary number of space (' ') characters, followed by a		with an arbitrary number of space (' ') characters, followed by a
	backslash ('\') character, immediately followed by the character that		backslash ('\') character, immediately followed by the character that
	was previously occupying the position where the fold occurred.		was previously occupying the position where the fold occurred.
	Continue in this manner until reaching the end of the text content.		Continue in this manner until reaching the end of the text content.
	Note that this algorithm naturally addresses the case where the		Note that this algorithm naturally addresses the case where the
	remainder of a folded line is still longer than the desired maximum,		remainder of a folded line is still longer than the desired maximum
	and hence needs to be folded again, ad infinitum.		and, hence, needs to be folded again, ad infinitum.
	The process described in this section is illustrated by the		The process described in this section is illustrated by the
	"fold_it_2()" function in Appendix A.		"fold_it_2()" function in Appendix A.
	8.2.2. Unfolding		8.2.2. Unfolding
	Scan the beginning of the text content for the header described in		Scan the beginning of the text content for the header described in
	Section 8.1.1. If the header is not present, exit (this text content		Section 8.1.1. If the header is not present, exit (this text content
	does not need to be unfolded).		does not need to be unfolded).
	Remove the 2-line header from the text content.		Remove the two-line header from the text content.
	For each line in the text content, from top-to-bottom, if the line		For each line in the text content, from top to bottom, if the line
	has a backslash ('\') character immediately followed by the end of		has a backslash ('\') character immediately followed by the end-of-
	line character sequence, and if the next line has a backslash ('\')		line character sequence and if the next line has a backslash ('\')
	character as the first non-space (' ') character, then the lines can		character as the first character that is not a space character (' '),
	be unfolded. Remove the first backslash ('\') character, the end of		then the lines can be unfolded. Remove the first backslash ('\')
	line character sequence, any leading space (' ') characters, and the		character, the end-of-line character sequence, any leading space
	second backslash ('\') character, which will bring up the next line.		(' ') characters, and the second backslash ('\') character, which
	Then continue to scan each line in the text content starting with the		will bring up the next line. Then, continue to scan each line in the
	current line (in case it was multiply folded).		text content starting with the current line (in case it was multiply
			folded).
	Continue in this manner until reaching the end of the text content.		Continue in this manner until reaching the end of the text content.
	The process described in this section is illustrated by the		The process described in this section is illustrated by the
	"unfold_it_2()" function in Appendix A.		"unfold_it_2()" function in Appendix A.
	9. Examples		9. Examples
	The following self-documenting examples illustrate folded text-based		The following self-documenting examples illustrate folded text-based
	content.		content.
	The source text content cannot be presented here, as it would again		The source text content cannot be presented here, as it would again
	be folded. Alas, only the results can be provided.		be folded. Alas, only the results can be provided.
	9.1. Example Showing Boundary Conditions		9.1. Example Showing Boundary Conditions
	This example illustrates boundary conditions. The input contains		This example illustrates boundary conditions. The input contains
	seven lines, each line one character longer than the previous line.		seven lines, each line one character longer than the previous line.
	Numbers for counting purposes. The default desired maximum column		Numbers are used for counting purposes. The default desired maximum
	value "69" is used.		column value "69" is used.
	9.1.1. Using '\'		9.1.1. Using '\'
	========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========		========== NOTE: '\' line wrapping per RFC 8792 ===========
	123456789012345678901234567890123456789012345678901234567890123456		123456789012345678901234567890123456789012345678901234567890123456
	1234567890123456789012345678901234567890123456789012345678901234567		1234567890123456789012345678901234567890123456789012345678901234567
	12345678901234567890123456789012345678901234567890123456789012345678		12345678901234567890123456789012345678901234567890123456789012345678
	123456789012345678901234567890123456789012345678901234567890123456789		123456789012345678901234567890123456789012345678901234567890123456789
	12345678901234567890123456789012345678901234567890123456789012345678\		12345678901234567890123456789012345678901234567890123456789012345678\
	90		90
	12345678901234567890123456789012345678901234567890123456789012345678\		12345678901234567890123456789012345678901234567890123456789012345678\
	901		901
	12345678901234567890123456789012345678901234567890123456789012345678\		12345678901234567890123456789012345678901234567890123456789012345678\
	9012		9012
	9.1.2. Using '\\'		9.1.2. Using '\\'
	========== NOTE: '\\' line wrapping per BCP XXX (RFC XXXX) ==========		========== NOTE: '\\' line wrapping per RFC 8792 ==========
	123456789012345678901234567890123456789012345678901234567890123456		123456789012345678901234567890123456789012345678901234567890123456
	1234567890123456789012345678901234567890123456789012345678901234567		1234567890123456789012345678901234567890123456789012345678901234567
	12345678901234567890123456789012345678901234567890123456789012345678		12345678901234567890123456789012345678901234567890123456789012345678
	123456789012345678901234567890123456789012345678901234567890123456789		123456789012345678901234567890123456789012345678901234567890123456789
	12345678901234567890123456789012345678901234567890123456789012345678\		12345678901234567890123456789012345678901234567890123456789012345678\
	\90		\90
	12345678901234567890123456789012345678901234567890123456789012345678\		12345678901234567890123456789012345678901234567890123456789012345678\
	\901		\901
	12345678901234567890123456789012345678901234567890123456789012345678\		12345678901234567890123456789012345678901234567890123456789012345678\
	\9012		\9012
	9.2. Example Showing Multiple Wraps of a Single Line		9.2. Example Showing Multiple Wraps of a Single Line
	This example illustrates what happens when a very long line needs to		This example illustrates what happens when a very long line needs to
	be folded multiple times. The input contains one line containing 280		be folded multiple times. The input contains one line containing 280
	characters. Numbers for counting purposes. The default desired		characters. Numbers are used for counting purposes. The default
	maximum column value "69" is used.		desired maximum column value "69" is used.
	9.2.1. Using '\'		9.2.1. Using '\'
	========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========		========== NOTE: '\' line wrapping per RFC 8792 ===========
	12345678901234567890123456789012345678901234567890123456789012345678\		12345678901234567890123456789012345678901234567890123456789012345678\
	90123456789012345678901234567890123456789012345678901234567890123456\		90123456789012345678901234567890123456789012345678901234567890123456\
	78901234567890123456789012345678901234567890123456789012345678901234\		78901234567890123456789012345678901234567890123456789012345678901234\
	56789012345678901234567890123456789012345678901234567890123456789012\		56789012345678901234567890123456789012345678901234567890123456789012\
	34567890		34567890
	9.2.2. Using '\\'		9.2.2. Using '\\'
	========== NOTE: '\\' line wrapping per BCP XXX (RFC XXXX) ==========		========== NOTE: '\\' line wrapping per RFC 8792 ==========
	12345678901234567890123456789012345678901234567890123456789012345678\		12345678901234567890123456789012345678901234567890123456789012345678\
	\9012345678901234567890123456789012345678901234567890123456789012345\		\9012345678901234567890123456789012345678901234567890123456789012345\
	\6789012345678901234567890123456789012345678901234567890123456789012\		\6789012345678901234567890123456789012345678901234567890123456789012\
	\3456789012345678901234567890123456789012345678901234567890123456789\		\3456789012345678901234567890123456789012345678901234567890123456789\
	\01234567890		\01234567890
	9.3. Example Showing "Smart" Folding		9.3. Example Showing "Smart" Folding
	This example illustrates how readability can be improved via "smart"		This example illustrates how readability can be improved via "smart"
	folding, whereby folding occurs at format-specific locations and		folding, whereby folding occurs at format-specific locations and
	format-specific indentations are used.		format-specific indentations are used.
	The text content was manually folded, since the script in the		The text content was manually folded, since the script in Appendix A
	appendix does not implement smart folding.		does not implement smart folding.
	Note that the headers are surrounded by different printable		Note that the headers are surrounded by different printable
	characters than shown in the script-generated examples.		characters than those shown in the script-generated examples.
	9.3.1. Using '\'		9.3.1. Using '\'
	[NOTE: '\' line wrapping per BCP XXX (RFC XXXX)]		[NOTE: '\' line wrapping per RFC 8792]
	<yang-library		<yang-library
	xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"		xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"
	xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">		xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
	<module-set>		<module-set>
	<name>config-modules</name>		<name>config-modules</name>
	<module>		<module>
	<name>ietf-interfaces</name>		<name>ietf-interfaces</name>
	<revision>2018-02-20</revision>		<revision>2018-02-20</revision>
	<namespace>\		<namespace>\
	urn:ietf:params:xml:ns:yang:ietf-interfaces\		urn:ietf:params:xml:ns:yang:ietf-interfaces\
	</namespace>		</namespace>
	</module>		</module>
	...		...
	</module-set>		</module-set>
	...		...
	</yang-library>		</yang-library>
	Below is the equivalent to the above, but it was folded using the		Below is the equivalent of the above, but it was folded using the
	script in the appendix.		script in Appendix A.
	========== NOTE: '\' line wrapping per BCP XXX (RFC XXXX) ===========		========== NOTE: '\' line wrapping per RFC 8792 ===========
	<yang-library		<yang-library
	xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"		xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"
	xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">		xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
	<module-set>		<module-set>
	<name>config-modules</name>		<name>config-modules</name>
	<module>		<module>
	<name>ietf-interfaces</name>		<name>ietf-interfaces</name>
	<revision>2018-02-20</revision>		<revision>2018-02-20</revision>
	<namespace>urn:ietf:params:xml:ns:yang:ietf-interfaces</namesp\		<namespace>urn:ietf:params:xml:ns:yang:ietf-interfaces</namesp\
	ace>		ace>
	</module>		</module>
	...		...
	</module-set>		</module-set>
	...		...
	</yang-library>		</yang-library>
	9.3.2. Using '\\'		9.3.2. Using '\\'
	[NOTE: '\\' line wrapping per BCP XXX (RFC XXXX)]		[NOTE: '\\' line wrapping per RFC 8792]
	<yang-library		<yang-library
	xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"		xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"
	xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">		xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
	<module-set>		<module-set>
	<name>config-modules</name>		<name>config-modules</name>
	<module>		<module>
	<name>ietf-interfaces</name>		<name>ietf-interfaces</name>
	<revision>2018-02-20</revision>		<revision>2018-02-20</revision>
	<namespace>\		<namespace>\
	\urn:ietf:params:xml:ns:yang:ietf-interfaces\		\urn:ietf:params:xml:ns:yang:ietf-interfaces\
	\</namespace>		\</namespace>
	</module>		</module>
	...		...
	</module-set>		</module-set>
	...		...
	</yang-library>		</yang-library>
	Below is the equivalent to the above, but it was folded using the		Below is the equivalent of the above, but it was folded using the
	script in the appendix.		script in Appendix A.
	========== NOTE: '\\' line wrapping per BCP XXX (RFC XXXX) ==========		========== NOTE: '\\' line wrapping per RFC 8792 ==========
	<yang-library		<yang-library
	xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"		xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-library"
	xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">		xmlns:ds="urn:ietf:params:xml:ns:yang:ietf-datastores">
	<module-set>		<module-set>
	<name>config-modules</name>		<name>config-modules</name>
	<module>		<module>
	<name>ietf-interfaces</name>		<name>ietf-interfaces</name>
	<revision>2018-02-20</revision>		<revision>2018-02-20</revision>
	skipping to change at page 17, line 5 ¶		skipping to change at line 734 ¶
	</module-set>		</module-set>
	...		...
	</yang-library>		</yang-library>
	9.4. Example Showing "Forced" Folding		9.4. Example Showing "Forced" Folding
	This example illustrates how invalid sequences in lines that do not		This example illustrates how invalid sequences in lines that do not
	have to be folded can be handled via forced folding, whereby the		have to be folded can be handled via forced folding, whereby the
	folding occurs even though unnecessary.		folding occurs even though unnecessary.
	The following line exceeds a 68-char max, thus demands folding		The following line exceeds a 68-char max and, thus, demands folding:
	123456789012345678901234567890123456789012345678901234567890123456789		123456789012345678901234567890123456789012345678901234567890123456789
	This line ends with a backslash \		This line ends with a backslash \
	This line ends with a backslash \		This line ends with a backslash \
	\ This line begins with a backslash		\ This line begins with a backslash
	Following is an indented 3x3 block of backslashes:		The following is an indented 3x3 block of backslashes:
	\\\		\\\
	\\\		\\\
	\\\		\\\
	The samples below were manually folded, since the script in the		The samples below were manually folded, since the script in the
	appendix does not implement forced folding.		appendix does not implement forced folding.
	Note that the headers are prefixed by a pound ('#') character, rather		Note that the headers are prefixed by a pound ('#') character, rather
	than surrounded by equal ('=') characters as shown in the script-		than surrounded by 'equals' ('=') characters as shown in the script-
	generated examples.		generated examples.
	9.4.1. Using '\'		9.4.1. Using '\'
	# NOTE: '\' line wrapping per BCP XXX (RFC XXXX)		# NOTE: '\' line wrapping per RFC 8792
	The following line exceeds a 68-char max, thus demands folding		The following line exceeds a 68-char max and, thus, demands folding:
	1234567890123456789012345678901234567890123456789012345678901234567\		1234567890123456789012345678901234567890123456789012345678901234567\
	89		89
	This line ends with a backslash \\		This line ends with a backslash \\
	This line ends with a backslash \\		This line ends with a backslash \\
	\ This line begins with a backslash		\ This line begins with a backslash
	Following is an indented 3x3 block of backslashes:		The following is an indented 3x3 block of backslashes:
	\\\\		\\\\
	\\\\		\\\\
	\\\		\\\
	9.4.2. Using '\\'		9.4.2. Using '\\'
	# NOTE: '\\' line wrapping per BCP XXX (RFC XXXX)
	The following line exceeds a 68-char max, thus demands folding		# NOTE: '\\' line wrapping per RFC 8792
			The following line exceeds a 68-char max and, thus, demands folding:
	1234567890123456789012345678901234567890123456789012345678901234567\		1234567890123456789012345678901234567890123456789012345678901234567\
	\89		\89
	This line ends with a backslash \		This line ends with a backslash \
	This line ends with a backslash \\		This line ends with a backslash \\
	\		\
	\ This line begins with a backslash		\ This line begins with a backslash
	Following is an indented 3x3 block of backslashes:		The following is an indented 3x3 block of backslashes:
	\\\\		\\\\
	\		\
	\\\\		\\\\
	\		\
	\\\		\\\
	10. Security Considerations		10. Security Considerations
	This BCP has no Security Considerations.		This document has no security considerations.
	11. IANA Considerations		11. IANA Considerations
	This BCP has no IANA Considerations.		This document has no IANA actions.
	12. References		12. References
	12.1. Normative References		12.1. Normative References
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	skipping to change at page 19, line 10 ¶		skipping to change at line 826 ¶
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	12.2. Informative References		12.2. Informative References
	[bash] "GNU Bash Manual",		[bash] "GNU Bash Manual",
	<https://www.gnu.org/software/bash/manual>.		<https://www.gnu.org/software/bash/manual>.
	[pyang] "An extensible YANG (RFC 6020/7950) validator.",		[pyang] "pyang", <https://pypi.org/project/pyang/>.
	<https://pypi.org/project/pyang/>.
	[RFC7749] Reschke, J., "The "xml2rfc" Version 2 Vocabulary",		[RFC7749] Reschke, J., "The "xml2rfc" Version 2 Vocabulary",
	RFC 7749, DOI 10.17487/RFC7749, February 2016,		RFC 7749, DOI 10.17487/RFC7749, February 2016,
	<https://www.rfc-editor.org/info/rfc7749>.		<https://www.rfc-editor.org/info/rfc7749>.
	[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",		[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
	RFC 7950, DOI 10.17487/RFC7950, August 2016,		RFC 7950, DOI 10.17487/RFC7950, August 2016,
	<https://www.rfc-editor.org/info/rfc7950>.		<https://www.rfc-editor.org/info/rfc7950>.
	[RFC7994] Flanagan, H., "Requirements for Plain-Text RFCs",		[RFC7994] Flanagan, H., "Requirements for Plain-Text RFCs",
	RFC 7994, DOI 10.17487/RFC7994, December 2016,		RFC 7994, DOI 10.17487/RFC7994, December 2016,
	<https://www.rfc-editor.org/info/rfc7994>.		<https://www.rfc-editor.org/info/rfc7994>.
	[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",		[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
	BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,		BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
	<https://www.rfc-editor.org/info/rfc8340>.		<https://www.rfc-editor.org/info/rfc8340>.
	[xiax] "The `xiax` Python Package",		[xiax] "The 'xiax' Python Package",
	<https://pypi.org/project/xiax/>.		<https://pypi.org/project/xiax/>.
	[xml2rfc] "Xml2rfc generates RFCs and IETF drafts from document		[xml2rfc] "xml2rfc", <https://pypi.org/project/xml2rfc/>.
	source in XML according to the IETF xml2rfc v2 and v3
	vocabularies.", <https://pypi.org/project/xml2rfc/>.
	[yang-doctors-thread]		[yang-doctors-thread]
	"[yang-doctors] automating yang doctor reviews",		Watsen, K., "[yang-doctors] automating yang doctor
	<https://mailarchive.ietf.org/arch/msg/yang-doctors/		reviews", message to the yang-doctors mailing list, 18
	DCfBqgfZPAD7afzeDFlQ1Xm2X3g>.		April 2018, <https://mailarchive.ietf.org/arch/msg/yang-
			doctors/DCfBqgfZPAD7afzeDFlQ1Xm2X3g>.
	[yanglint]		[yanglint] "yanglint", commit 1b7d73d, February 2020,
	"A feature-rich tool for validation and conversion of the
	schemas and YANG modeled data.",
	<https://github.com/CESNET/libyang#yanglint>.		<https://github.com/CESNET/libyang#yanglint>.
	Appendix A. Bash Shell Script: rfcfold		Appendix A. Bash Shell Script: rfcfold
	This non-normative appendix section includes a Bash [bash] shell		This non-normative appendix includes a Bash shell script [bash] that
	script that can both fold and unfold text content using both the		can both fold and unfold text content using both the single and
	single and double backslash strategies described in Section 7 and		double backslash strategies described in Sections 7 and 8,
	Section 8 respectively.		respectively. This shell script, called 'rfcfold', is maintained at
			<https://github.com/ietf-tools/rfcfold>.
	This script is intended to be applied to a single text content		This script is intended to be applied to a single text content
	instance. If it is desired to fold or unfold text content instances		instance. If it is desired to fold or unfold text content instances
	within a larger document (e.g., an Internet draft or RFC), then		within a larger document (e.g., an Internet-Draft or RFC), then
	another tool must be used to extract the content from the larger		another tool must be used to extract the content from the larger
	document before utilizing this script.		document before utilizing this script.
	For readability purposes, this script forces the minimally supported		For readability purposes, this script forces the minimum supported
	line length to be eight characters longer than the raw header text		line length to be eight characters longer than the raw header text
	defined in Section 7.1.1 and Section 8.1.1 so as to ensure that the		defined in Sections 7.1.1 and 8.1.1 so as to ensure that the header
	header can be wrapped by a space (' ') character and three equal		can be wrapped by a space (' ') character and three 'equals' ('=')
	('=') characters on each side of the raw header text.		characters on each side of the raw header text.
	When a TAB character is detected in the input file, this script exits		When a tab character is detected in the input file, this script exits
	with the error message:		with the following error message:
	Error: infile contains a TAB character, which is not allowed.		Error: infile contains a tab character, which is not allowed.
	This script tests for the availability of GNU awk (gawk), in order to		This script tests for the availability of GNU awk (gawk), in order to
	test for ASCII-based control characters and non-ASCII characters in		test for ASCII-based control characters and non-ASCII characters in
	the input file (see below). Note that testing revealed flaws in the		the input file (see below). Note that testing revealed flaws in the
	default version of `awk` on some platforms. As the use of `gawk` is		default version of 'awk' on some platforms. As this script uses
	only used to issue warning messages, if `gawk` of not found, this		'gawk' only to issue warning messages, if 'gawk' is not found, this
	script issues the debug message:		script issues the following debug message:
	Debug: no GNU Awk, skipping checks for special characters.		Debug: no GNU awk; skipping checks for special characters.
	When `gawk` is available (see above) and ASCII-based control		When 'gawk' is available (see above) and ASCII-based control
	characters are detected in the input file, this script issues the		characters are detected in the input file, this script issues the
	warning message:		following warning message:
	Warning: infile contains ASCII control characters (unsupported).		Warning: infile contains ASCII control characters (unsupported).
	When `gawk` is available (see above) and non-ASCII characters are		When 'gawk' is available (see above) and non-ASCII characters are
	detected in the input file, this script issues the warning message:		detected in the input file, this script issues the following warning
			message:
	Warning: infile contains non-ASCII characters (unsupported).		Warning: infile contains non-ASCII characters (unsupported).
	This script does not implement the whitespace-avoidance logic		This script does not implement the whitespace-avoidance logic
	described in Section 7.2.1. In such case, the script will exit with		described in Section 7.2.1. In such a case, the script will exit
	the following message:		with the following error message:
	Error: infile has a space character occurring on the		Error: infile has a space character occurring on the folding
	folding column. This file cannot be folded using the		column. This file cannot be folded using the '\' strategy.
	'\' strategy.
	While this script can unfold input that contains forced foldings, it		While this script can unfold input that contains forced foldings, it
	is unable to fold files that would require forced foldings. Forced		is unable to fold files that would require forced foldings. Forced
	folding is described in Section 7.2.1 and Section 8.2.1. When being		folding is described in Sections 7.2.1 and 8.2.1. When being asked
	asked to fold a file that would require forced folding, the script		to fold a file that would require forced folding, the script will
	will instead exit with the following message:		instead exit with one of the following error messages:
	For '\':		For '\':
	Error: infile has a line ending with a '\' character.		Error: infile has a line ending with a '\' character. This file
	This file cannot be folded using the '\' strategy without		cannot be folded using the '\' strategy without there being false
	there being false positives produced in the unfolding		positives produced in the unfolding (i.e., this script does not
	(i.e., this script does not force-fold such lines, as		force-fold such lines, as described in RFC 8792).
	described in BCP XXX, RFC XXXX).
	For '\\':		For '\\':
	Error: infile has a line ending with a '\' character		Error: infile has a line ending with a '\' character followed by a
	followed by a '\' character as the first non-space		'\' character as the first non-space character on the next line.
	character on the next line. This script cannot fold		This script cannot fold this file using the '\\' strategy without
	this file using '\\' strategy without there being		there being false positives produced in the unfolding (i.e., this
	false positives produced in the unfolding (i.e., this		script does not force-fold such lines, as described in RFC 8792).
	script does not force-fold such lines, as described
	in BCP XXX, RFC XXXX).
	Shell-level end-of-line backslash ('\') characters have been		Shell-level end-of-line backslash ('\') characters have been
	purposely added to the script so as to ensure that the script is		purposely added to the script so as to ensure that the script is
	itself not folded in this document, thus simplifying the ability to		itself not folded in this document, thus simplifying the ability to
	copy/paste the script for local use. As should be evident by the		copy/paste the script for local use. As should be evident by the
	lack of the mandatory header described in Section 7.1.1, these		lack of the mandatory header described in Section 7.1.1, these
	backslashes do not designate a folded line, such as described in		backslashes do not designate a folded line (e.g., as described in
	Section 7.		Section 7).
	<CODE BEGINS>
			<CODE BEGINS> file "rfcfold"
	#!/bin/bash --posix		#!/bin/bash --posix
	# This script may need some adjustments to work on a given system.		# This script may need some adjustments to work on a given system.
	# For instance, the utility `gsed` may need to be installed.		# For instance, the utility 'gsed' may need to be installed.
	# Also, please be advised that `bash` (not `sh`) must be used.		# Also, please be advised that 'bash' (not 'sh') must be used.
	# Copyright (c) 2019 IETF Trust, Kent Watsen, and Erik Auerswald.		# Copyright (c) 2020 IETF Trust, Kent Watsen, and Erik Auerswald.
	# All rights reserved.		# All rights reserved.
	#		#
	# Redistribution and use in source and binary forms, with or without		# Redistribution and use in source and binary forms, with or without
	# modification, are permitted provided that the following conditions		# modification, are permitted provided that the following conditions
	# are met:		# are met:
	#		#
	# * Redistributions of source code must retain the above copyright		# * Redistributions of source code must retain the above copyright
	# notice, this list of conditions and the following disclaimer.		# notice, this list of conditions and the following disclaimer.
	#		#
	# * Redistributions in binary form must reproduce the above		# * Redistributions in binary form must reproduce the above
	skipping to change at page 22, line 23 ¶		skipping to change at line 970 ¶
	# provided with the distribution.		# provided with the distribution.
	#		#
	# * Neither the name of Internet Society, IETF or IETF Trust, nor		# * Neither the name of Internet Society, IETF or IETF Trust, nor
	# the names of specific contributors, may be used to endorse or		# the names of specific contributors, may be used to endorse or
	# promote products derived from this software without specific		# promote products derived from this software without specific
	# prior written permission.		# prior written permission.
	#		#
	# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS		# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
	# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT		# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
	# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS		# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
	# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE		# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
	# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,		# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
	# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES		# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
	# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR		# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
	# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)		# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,		# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)		# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF		# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
	# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.		# ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	print_usage() {		print_usage() {
	printf "\n"		printf "\n"
	printf "Folds or unfolds the input text file according to BCP XXX"		printf "Folds or unfolds the input text file according to"
	printf " (RFC XXXX).\n"		printf " RFC 8792.\n"
	printf "\n"		printf "\n"
	printf "Usage: rfcfold [-h] [-d] [-q] [-s <strategy>] [-c <col>]"		printf "Usage: rfcfold [-h] [-d] [-q] [-s <strategy>] [-c <col>]"
	printf " [-r] -i <infile> -o <outfile>\n"		printf " [-r] -i <infile> -o <outfile>\n"
	printf "\n"		printf "\n"
	printf " -s: strategy to use, '1' or '2' (default: try 1,"		printf " -s: strategy to use, '1' or '2' (default: try 1,"
	printf " else 2)\n"		printf " else 2)\n"
	printf " -c: column to fold on (default: 69)\n"		printf " -c: column to fold on (default: 69)\n"
	printf " -r: reverses the operation\n"		printf " -r: reverses the operation\n"
	printf " -i: the input filename\n"		printf " -i: the input filename\n"
	printf " -o: the output filename\n"		printf " -o: the output filename\n"
	skipping to change at page 23, line 16 ¶		skipping to change at line 1011 ¶
	# global vars, do not edit		# global vars, do not edit
	strategy=0 # auto		strategy=0 # auto
	debug=0		debug=0
	quiet=0		quiet=0
	reversed=0		reversed=0
	infile=""		infile=""
	outfile=""		outfile=""
	maxcol=69 # default, may be overridden by param		maxcol=69 # default, may be overridden by param
	col_gvn=0 # maxcol overridden?		col_gvn=0 # maxcol overridden?
	hdr_txt_1="NOTE: '\\' line wrapping per BCP XXX (RFC XXXX)"		hdr_txt_1="NOTE: '\\' line wrapping per RFC 8792"
	hdr_txt_2="NOTE: '\\\\' line wrapping per BCP XXX (RFC XXXX)"		hdr_txt_2="NOTE: '\\\\' line wrapping per RFC 8792"
	equal_chars="======================================================="		equal_chars="======================================================="
	space_chars=" "		space_chars=" "
	temp_dir=""		temp_dir=""
	prog_name='rfcfold'		prog_name='rfcfold'
	# functions for diagnostic messages		# functions for diagnostic messages
	prog_msg() {		prog_msg() {
	if [[ "$quiet" -eq 0 ]]; then		if [[ "$quiet" -eq 0 ]]; then
	format_string="${prog_name}: $1: %s\n"		format_string="${prog_name}: $1: %s\n"
	shift		shift
	skipping to change at page 24, line 26 ¶		skipping to change at line 1070 ¶
	return 1		return 1
	fi		fi
	# where to fold		# where to fold
	foldcol=$(expr "$maxcol" - 1) # for the inserted '\' char		foldcol=$(expr "$maxcol" - 1) # for the inserted '\' char
	# ensure input file doesn't contain whitespace on the fold column		# ensure input file doesn't contain whitespace on the fold column
	grep -q "^\(.\{$foldcol\}\)\{1,\} " "$infile"		grep -q "^\(.\{$foldcol\}\)\{1,\} " "$infile"
	if [[ $? -eq 0 ]]; then		if [[ $? -eq 0 ]]; then
	err "infile '$infile' has a space character occurring on the"\		err "infile '$infile' has a space character occurring on the"\
	"folding column. This file cannot be folded using the"\		"folding column. This file cannot be folded using the"\
	"'\\' strategy."		"'\\' strategy."
	return 1		return 1
	fi		fi
	# center header text		# center header text
	length=$(expr ${#hdr_txt_1} + 2)		length=$(expr ${#hdr_txt_1} + 2)
	left_sp=$(expr \( "$maxcol" - "$length" \) / 2)		left_sp=$(expr \( "$maxcol" - "$length" \) / 2)
	right_sp=$(expr "$maxcol" - "$length" - "$left_sp")		right_sp=$(expr "$maxcol" - "$length" - "$left_sp")
	header=$(printf "%.*s %s %.*s" "$left_sp" "$equal_chars"\		header=$(printf "%.*s %s %.*s" "$left_sp" "$equal_chars"\
	"$hdr_txt_1" "$right_sp" "$equal_chars")		"$hdr_txt_1" "$right_sp" "$equal_chars")
	skipping to change at page 25, line 4 ¶		skipping to change at line 1096 ¶
	< "$infile" >> "$outfile" 2> /dev/null		< "$infile" >> "$outfile" 2> /dev/null
	if [[ $? -ne 0 ]]; then		if [[ $? -ne 0 ]]; then
	return 1		return 1
	fi		fi
	return 0		return 0
	}		}
	fold_it_2() {		fold_it_2() {
	# where to fold		# where to fold
	foldcol=$(expr "$maxcol" - 1) # for the inserted '\' char		foldcol=$(expr "$maxcol" - 1) # for the inserted '\' char
	# ensure input file doesn't contain the fold-sequence already		# ensure input file doesn't contain the fold-sequence already
	if [[ -n "$("$SED" -n '/\\$/{N;s/\\\n[ ]*\\/&/p;D}' "$infile")" ]]		if [[ -n "$("$SED" -n '/\\$/{N;s/\\\n[ ]*\\/&/p;D}' "$infile")" ]]
	then		then
	err "infile '$infile' has a line ending with a '\\' character"\		err "infile '$infile' has a line ending with a '\\' character"\
	"followed by a '\\' character as the first non-space"\		"followed by a '\\' character as the first non-space"\
	"character on the next line. This script cannot fold"\		"character on the next line. This script cannot fold"\
	"this file using '\\\\' strategy without there being"\		"this file using the '\\\\' strategy without there being"\
	"false positives produced in the unfolding."		"false positives produced in the unfolding."
	return 1		return 1
	fi		fi
	# center header text		# center header text
	length=$(expr ${#hdr_txt_2} + 2)		length=$(expr ${#hdr_txt_2} + 2)
	left_sp=$(expr \( "$maxcol" - "$length" \) / 2)		left_sp=$(expr \( "$maxcol" - "$length" \) / 2)
	right_sp=$(expr "$maxcol" - "$length" - "$left_sp")		right_sp=$(expr "$maxcol" - "$length" - "$left_sp")
	header=$(printf "%.*s %s %.*s" "$left_sp" "$equal_chars"\		header=$(printf "%.*s %s %.*s" "$left_sp" "$equal_chars"\
	"$hdr_txt_2" "$right_sp" "$equal_chars")		"$hdr_txt_2" "$right_sp" "$equal_chars")
	skipping to change at page 25, line 34 ¶		skipping to change at line 1127 ¶
	echo "" >> "$outfile"		echo "" >> "$outfile"
	"$SED" 's/\(.\{'"$foldcol"'\}\)\(..\)/\1\\\n\\\2/;t M;b;:M;P;D;'\		"$SED" 's/\(.\{'"$foldcol"'\}\)\(..\)/\1\\\n\\\2/;t M;b;:M;P;D;'\
	< "$infile" >> "$outfile" 2> /dev/null		< "$infile" >> "$outfile" 2> /dev/null
	if [[ $? -ne 0 ]]; then		if [[ $? -ne 0 ]]; then
	return 1		return 1
	fi		fi
	return 0		return 0
	}		}
	fold_it() {		fold_it() {
	# ensure input file doesn't contain a TAB		# ensure input file doesn't contain a tab
	grep -q $'\t' "$infile"		grep -q $'\t' "$infile"
	if [[ $? -eq 0 ]]; then		if [[ $? -eq 0 ]]; then
	err "infile '$infile' contains a TAB character, which is not"\		err "infile '$infile' contains a tab character, which is not"\
	"allowed."		"allowed."
	return 1		return 1
	fi		fi
	# folding of input containing ASCII control or non-ASCII characters		# folding of input containing ASCII control or non-ASCII characters
	# may result in a wrong folding column and is not supported		# may result in a wrong folding column and is not supported
	if type gawk > /dev/null 2>&1; then		if type gawk > /dev/null 2>&1; then
	env LC_ALL=C gawk '/[\000-\014\016-\037\177]/{exit 1}' "$infile"\		env LC_ALL=C gawk '/[\000-\014\016-\037\177]/{exit 1}' "$infile"\
	|| warn "infile '$infile' contains ASCII control characters"\		|| warn "infile '$infile' contains ASCII control characters"\
	"(unsupported)."		"(unsupported)."
	env LC_ALL=C gawk '/[^\000-\177]/{exit 1}' "$infile"\		env LC_ALL=C gawk '/[^\000-\177]/{exit 1}' "$infile"\
	|| warn "infile '$infile' contains non-ASCII characters"\		|| warn "infile '$infile' contains non-ASCII characters"\
	"(unsupported)."		"(unsupported)."
	else		else
	dbg "no GNU Awk, skipping checks for special characters."		dbg "no GNU awk; skipping checks for special characters."
	fi		fi
	# check if file needs folding		# check if file needs folding
	testcol=$(expr "$maxcol" + 1)		testcol=$(expr "$maxcol" + 1)
	grep -q ".\{$testcol\}" "$infile"		grep -q ".\{$testcol\}" "$infile"
	if [[ $? -ne 0 ]]; then		if [[ $? -ne 0 ]]; then
	dbg "nothing to do; copying infile to outfile."		dbg "nothing to do; copying infile to outfile."
	cp "$infile" "$outfile"		cp "$infile" "$outfile"
	return 255		return 255
	fi		fi
	skipping to change at page 26, line 30 ¶		skipping to change at line 1171 ¶
	if [[ "$strategy" -eq 2 ]]; then		if [[ "$strategy" -eq 2 ]]; then
	fold_it_2		fold_it_2
	return $?		return $?
	fi		fi
	quiet_sav="$quiet"		quiet_sav="$quiet"
	quiet=1		quiet=1
	fold_it_1		fold_it_1
	result=$?		result=$?
	quiet="$quiet_sav"		quiet="$quiet_sav"
	if [[ "$result" -ne 0 ]]; then		if [[ "$result" -ne 0 ]]; then
	dbg "Folding strategy '1' didn't succeed, trying strategy '2'..."		dbg "Folding strategy '1' didn't succeed; trying strategy '2'..."
	fold_it_2		fold_it_2
	return $?		return $?
	fi		fi
	return 0		return 0
	}		}
	unfold_it_1() {		unfold_it_1() {
	temp_dir=$(mktemp -d)		temp_dir=$(mktemp -d)
	# output all but the first two lines (the header) to wip file		# output all but the first two lines (the header) to wip file
	skipping to change at page 30, line 13 ¶		skipping to change at line 1343 ¶
	<CODE ENDS>		<CODE ENDS>
	Acknowledgements		Acknowledgements
	The authors thank the RFC Editor for confirming that there was		The authors thank the RFC Editor for confirming that there was
	previously no set convention, at the time of this document's		previously no set convention, at the time of this document's
	publication, for handling long lines in source code inclusions, thus		publication, for handling long lines in source code inclusions, thus
	instigating this work.		instigating this work.
	The authors thank the following folks for their various contributions		The authors thank the following folks for their various contributions
	while producing this document (sorted by first name): Benoit Claise,		while producing this document (sorted by first name): Ben Kaduk,
	Ben Kaduk, Gianmarco Bruno, Italo Busi, Joel Jaeggli, Jonathan		Benoit Claise, Gianmarco Bruno, Italo Busi, Joel Jaeggli, Jonathan
	Hansford, Lou Berger, Martin Bjorklund, and Rob Wilton.		Hansford, Lou Berger, Martin Bjorklund, and Rob Wilton.
	Authors' Addresses		Authors' Addresses
	Kent Watsen		Kent Watsen
	Watsen Networks		Watsen Networks
	EMail: kent+ietf@watsen.net		Email: kent+ietf@watsen.net
	Erik Auerswald		Erik Auerswald
	Individual Contributor		Individual Contributor
	EMail: auerswal@unix-ag.uni-kl.de		Email: auerswal@unix-ag.uni-kl.de
	Adrian Farrel		Adrian Farrel
	Old Dog Consulting		Old Dog Consulting
	EMail: adrian@olddog.co.uk		Email: adrian@olddog.co.uk
	Qin Wu		Qin Wu
	Huawei Technologies		Huawei Technologies
	EMail: bill.wu@huawei.com		Email: bill.wu@huawei.com
End of changes. 131 change blocks.
	348 lines changed or deleted		334 lines changed or added
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