3.9.1. "align" Attribute
o "left" (default)
3.9.2. "width" Attribute
Deprecated. In earlier versions of this format, <vspace> was often
used to get an extra blank line in a list element; in the v3
vocabulary, that can be done instead by using multiple <t> elements
inside the <li> element. Other uses have no direct replacement.
This element appears as a child element of <t> (Section 2.53).
Content model: this element does not have any contents.
3.10.1. "blankLines" Attribute
The discussion of the use of SVG can be found in [RFC7996]. This
element is part of the namespace "http://www.w3.org/2000/svg".
5. Use of CDATA Structures and Escaping
A common problem authors have with <artwork> and <sourcecode>
elements is that the XML processor returns errors if the text in the
artwork contains either the "&" or "<" character, or the string
"]]>". To avoid these problems, the "&" and "<" characters may be
escaped using the strings "&" and "<", respectively; the "]]>"
string can be represented as "]]>". Alternatively, they may be
surrounded in a CDATA structure: "<![CDATA]>". For example:
allowed-chars = "." | "," | "&" | "<" | ">" | "|"
allowed-chars = "." | "," | "&" | "<" | ">" | "|"
<![CDATA[ allowed-chars = "." | "," | "&" | "<" | ">" | "|"]]>
Using CDATA is not a panacea, but it does help prevent having to use
escapes in places where using escapes can cause other problems, such
as difficulty of inclusion from other documents.
6. Internationalization Considerations
This format is based on [XML] and thus does not have any issues
representing arbitrary Unicode [UNICODE] characters in text content.
The RFC Series Editor may restrict some of the characters that can be
used in a particular RFC; the rules for such restrictions are covered
7. Security Considerations
The "name" attribute of the <artwork> element (Section 2.5.5) can be
used to derive a filename for saving to a local file system.
Trusting this kind of information without pre-processing is a known
security risk; see Section 4.3 of [RFC6266] for more information.
The "src" attribute of the <artwork> element can be used to read
files from the local system. Processing tools must be careful to not
accept dangerous values for the filename, particularly those that
contain absolute references outside the current directory.
The "type" attribute of the <artwork> and <sourcecode> elements is
meant to encourage formatters to automatically extract known types of
content from an RFC or Internet-Draft. While extraction is probably
safe, those tools might also think that they could further process
the extracted content, such as by rendering artwork or executing
code. Doing so without first sanity-checking the extracted content
is clearly a terrible idea from a security perspective. More
generally, a tool that is reading XML input needs to be suspicious of
any content that it intends to post-process.
When there is an external reference to a URL, a processor or renderer
should fetch the content into a sandbox and should have only a
localized impact on the document processing and rendering.
All security considerations related to XML processing are relevant as
well (see Section 7 of [RFC3470]).
8. IANA Considerations
8.1. Internet Media Type Registration
IANA maintains the registry of Internet Media Types [RFC6838] at
This document updates the specification for the Internet Media Type
"application/rfc+xml" from the one in [RFC7749]. The following has
been registered with IANA.
Type name: application
Subtype name: rfc+xml
Required parameters: There are no required parameters.
Optional parameters: "charset": This parameter has identical
semantics to the charset parameter of the "application/xml" Media
Type specified in Section 9.1 of [RFC7303].
Encoding considerations: Identical to those of "application/xml" as
described in Section 9.1 of [RFC7303].
Security considerations: As defined in Section 7. In addition, as
this Media Type uses the "+xml" convention, it inherits the
security considerations described in Section 10 of [RFC7303].
Interoperability considerations: Different implementations of this
format have had interoperability issues. It is not expected that
publication of this application will cause those implementations
to be fixed.
Published specification: This specification.
Applications that use this Media Type: Applications that transform
xml2rfc to output representations such as plain text or HTML, plus
additional analysis tools.
Fragment identifier considerations: The "anchor" attribute is used
for assigning document-wide unique identifiers that can be used as
shorthand pointers, as described in [XPOINTER].
Deprecated alias names for this type: None
Magic number(s): As specified for "application/xml" in [RFC7303].
File extension(s): .xml or .rfcxml when disambiguation from other
XML files is needed
Macintosh file type code(s): TEXT
Person & email address to contact for further information: See the
Author's Address section of RFC 7991.
Intended usage: COMMON
Restrictions on usage: None
Author: See the Author's Address section of RFC 7991.
Change controller: RFC Series Editor (firstname.lastname@example.org)
8.2. Link Relation Registration
IANA has registered "convertedFrom" in the "Link Relation Types"
Relation Name: convertedFrom
Description: The document linked to was later converted to the
document that contains this link relation. For example, an RFC can
have a link to the Internet-Draft that became the RFC; in that case,
the link relation would be "convertedFrom".
Appendix A. Front-Page ("Boilerplate") Generation
The values listed here will be defined by the RFC Series Editor.
Those listed here are believed to be the current values in use.
A.1. The "ipr" Attribute
This attribute value can take a long list of values, each of which
describes an IPR policy for the document (Section 2.45.5). The
values are not the result of a grand design, but they remain simply
for historic reasons. Of these values, only a few are currently in
use; all others are supported by various tools for backwards
compatibility with old source files.
Note: Some variations of the boilerplate are selected based on the
document's date; therefore, it is important to specify the "year",
"month", and "day" attributes of the <date> element when archiving
the XML source of an Internet-Draft on the day of submission.
_Disclaimer: THIS ONLY PROVIDES IMPLEMENTATION INFORMATION. IF YOU
NEED LEGAL ADVICE, PLEASE CONTACT A LAWYER._ For further
information, refer to <http://trustee.ietf.org/docs/IETF-Copyright-FAQ.pdf>.
For the current "Copyright Notice" text, the submissionType attribute
of the <rfc> element (Section 2.45.12) determines whether a statement
about "Code Components" is inserted (which is the case for the value
"IETF", which is the default). Other values, such as "independent",
suppress this part of the text.
A.1.1. Current Values: "*trust200902"
The name for these values refers to version 2.0 of the IETF Trust's
"Legal Provisions Relating to IETF Documents", sometimes simply
called the "TLP", which went into effect on February 15, 2009
[TLP2.0]. Updates to the document were published on September 12,
2009 [TLP3.0] and on December 28, 2009 [TLP4.0], modifying the
license for code components (see <http://trustee.ietf.org/license-info/> for further information). The actual text is located
in Section 6 ("Text to Be Included in IETF Documents") of these
The prep tool automatically produces the "correct" text, depending on
the document's date information (see above):
| TLP | starting with publication date |
| [TLP3.0] | 2009-11-01 |
| [TLP4.0] | 2010-04-01 |
The TLP was again updated in March 2015 [TLP5.0], but the changes
made in that version do not affect the boilerplate text.
This value should be used unless one of the more specific
"*trust200902" values is a better fit. It produces the text in
Sections 6.a and 6.b of the TLP.
This produces the additional text from Section 6.c.i of the TLP:
This document may not be modified, and derivative works of it may
not be created, except to format it for publication as an RFC or
to translate it into languages other than English.
Note: this clause is incompatible with RFCs that are published on
the Standards Track.
This produces the additional text from Section 6.c.ii of the TLP:
This document may not be modified, and derivative works of it may
not be created, and it may not be published except as an
Note: this clause is incompatible with RFCs.
This produces the additional text from Section 6.c.iii of the TLP,
frequently called the "pre-5378 escape clause" referring to changes
introduced in [RFC5378]:
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s)
controlling the copyright in such materials, this document may not
be modified outside the IETF Standards Process, and derivative
works of it may not be created outside the IETF Standards Process,
except to format it for publication as an RFC or to translate it
into languages other than English.
See Section 4 of <http://trustee.ietf.org/docs/
IETF-Copyright-FAQ.pdf> for further information about when to use
Note: this text appears under "Copyright Notice", unless the
document was published before November 2009, in which case it
appears under "Status of This Memo".
A.1.2. Historic Values
A.1.2.1. Historic Values: "*trust200811"
The attribute values "trust200811", "noModificationTrust200811", and
"noDerivativesTrust200811" are similar to their "trust200902"
counterparts, except that they use text specified in [TLP1.0].
A.1.2.2. Historic Values: "*3978"
The attribute values "full3978", "noModification3978", and
"noDerivatives3978" are similar to their counterparts above, except
that they use text specified in [RFC3978].
A.1.2.3. Historic Values: "*3667"
The attribute values "full3667", "noModification3667", and
"noDerivatives3667" are similar to their counterparts above, except
that they use text specified in [RFC3667].
A.1.2.4. Historic Values: "*2026"
The attribute values "full2026" and "noDerivativeWorks2026" are
similar to their counterparts above, except that they use text
specified in Section 10 of [RFC2026].
The special value "none" was also used back then; it denied the IETF
any rights beyond publication as an Internet-Draft.
A.2. The "submissionType" Attribute
The RFC Editor publishes documents from different "document streams",
of which the "IETF stream" is the most prominent. Other streams are
the "Independent Submissions stream" (used for things such as
discussion of Internet-related technologies that are not part of the
IETF agenda), the "IAB stream" (Internet Architecture Board), and the
"IRTF stream" (Internet Research Task Force).
The values for the attribute are "IETF" (the default value),
"independent", "IAB", and "IRTF".
Historically, this attribute did not affect the final appearance of
RFCs, except for subtle differences in copyright notices. Nowadays
(as of [RFC7841]), the stream name appears in the first line of the
front page, and it also affects the text in the "Status of This Memo"
For current documents, setting the "submissionType" attribute will
have the following effect:
o For RFCs, the stream name appears in the upper left corner of the
first page (in Internet-Drafts, this is either "Network Working
Group" or the value of the <workgroup> element).
o For RFCs, it affects the whole "Status of This Memo" section (see
Section 3.2 of [RFC7841]).
o For all RFCs and Internet-Drafts, it determines whether the
"Copyright Notice" section mentions the Copyright on Code
Components (see Section 6 of the TLP ("Text to Be Included in IETF
A.3. The "consensus" Attribute
For some of the publication streams (see Appendix A.2), the "Status
of This Memo" section depends on whether there was a consensus to
publish (again, see Section 3.4 of [RFC7841]).
The consensus attribute can be used to supply this information. The
acceptable values are "true" (the default) and "false"; "yes" and
"no" from v2 are deprecated.
The effect of this value for the various streams is:
o "independent": none.
o "IAB": mention that there was an IAB consensus.
o "IETF": mention that there was an IETF consensus.
o "IRTF": mention that there was a research group consensus (where
the name of the research group is extracted from the <workgroup>
Appendix B. The v3 Format and Processing Tools
This section describes topics that are specific to v3 processing
tools. Note that there is some discussion of tools in the main body
of the document as well. For example, some elements have
descriptions of how a processing tool might create output from the
The expected design of the tools that will be used with v3 documents
o A "prep tool" that takes a v3 document, makes many checks, adds
and changes many attribute values, and creates a file that is a
"prepared document". The prepared document is a valid v3
document. The prep tool is described in [RFC7998].
The prep tool is expected to have many modes:
* RFC mode -- The mode used by the RFC Editor to process the
input from one of the RFC streams and to process XML produced
during the RFC editing process. The restrictions on the
canonical XML for RFCs, as well as how the non-canonical
formats will look, are described at
* Draft mode -- The mode used by the Internet-Draft submission
tool. The restrictions for the XML from this mode will be
* Diagnostic mode -- A mode that can be used by document authors
to look for errors or warnings before they submit their
documents for publication.
* Consolidation mode -- Produces output where no external
resources are required to render the file output. This
includes expanding the XInclude entities and DTD entities in
place, and changing all elements that have "src" attributes
with external links into either "data:" URI or content for the
element, as specified in [RFC7998].
o Formatting tools that will create HTML, PDF, plain text, and
possibly other output formats. These formatters will be created
by the IETF, but others can create such tools as well. The IETF
tools are expected to take prepared documents as input.
There may also be processing tools that are meant to run on the
computers of authors. These tools may be used to produce interim
versions of the non-canonical representations so that authors can see
how their XML might later be rendered, to create documents in
representations different than those supported by the RFC Editor, to
possibly create documents that are not meant to be Internet-Drafts or
RFCs, and to convert XML that has external information into XML that
has that external information included.
The prep tool is expected to have clear error reporting, giving more
context than just a line number. For example, the error messages
should differentiate between errors in XML and those from the v3
In v2, the grammar was specified as a DTD. In v3, the grammar is
specified only as RELAX Next Generation (RNG). This means that tools
need to work from the RNG, not from a DTD. Some of the features of
the v3 grammar cannot be specified as a DTD.
B.1. Including External Text with XInclude
All tools for the v3 format are expected to support XInclude
[XInclude]. XInclude specifies a processing model and syntax for
general-purpose inclusion of information that is either on the
Internet or local to the user's computer.
In the v3 syntax, XInclude is expressed as the <xi:include> element.
To use this element, you need to include the "xi" namespace in the
<rfc> element; that is, you need to specify
as one of the attributes in the <rfc> element.
The most common way to use <xi:include> is to pull in references that
are already formed as XML. Currently, this can be done from
xml2rfc.tools.ietf.org, but later this is expected to be from the RFC
Editor. For example, if a document has three normative references,
all RFCs, the document might contain:
<xi:include> can be used anywhere an XML element could be used (but
not where free text is used). For example, if three Internet-Drafts
are all including a particular paragraph or section verbatim, that
text can be kept either in a file or somewhere on the web and can be
included with <xi:include>. An example of pulling something from the
local disk would be:
In general, XInclude should be used instead of ENTITY references and
XML Processing Instructions (PIs) that allow external inclusions.
B.2. Anchors and IDs
People writing and reading Internet-Drafts and RFCs often want to
make reference to specific locations in those documents. In the case
of RFC authors, it is common to want to reference another part of
their document, such as "see Section 3.2 of this document." Readers,
on the other hand, want to reference parts of documents that they
didn't write, such as "see Section 3.2 of RFC 6949." The XML
vocabulary in this document attempts to support both sets of people.
Authors can leave anchors in a document that can later be used for
references with the "anchor" attribute. Anchors can be included in
the numerous elements. The author can then refer to that anchor in
the "target" attribute of the <xref> element.
Readers can refer to any element that has an "anchor" attribute by
that attribute. Note, however, that most of the time, elements won't
have anchors. In the common case, the reader wants to refer to an
element that does not have an "anchor" attribute, but that element
has a "pn" attribute.
Processing tools add the "pn" attribute to many elements during
processing. This attribute and its value are automatically generated
by the tool if the attribute is not there; if the attribute is
already there, the tool may replace the value.
B.2.1. Overlapping Values
In the HTML representation of this XML vocabulary, both anchors and
"pn" attributes will be used in the "id" attributes of elements.
Thus, there can be no overlap between the names entered in "anchor"
attributes, in "slugifiedName" attributes, and those that are
generated for the "pn" attributes. Also, there are some values for
the "anchor" values that are reserved for sections, and those
sections can only have those anchor values.
The following rules prevent this overlap:
o "pn" for regular sections always has the format "s-nnn", where
"nnn" is the section number, or the appendix identifier (which
starts with a letter). For example, this would be "s-2.1.3" for
Section 2.1.3 and "s-a" for Appendix A. For the <abstract>
element, it is always "s-abstract". For the <note> element, it is
always "s-note-nnn", where "nnn" is a sequential value. For
sections in the <boilerplate> element, it is always
"s-boilerplate-nnn", where "nnn" is a sequential value.
o "pn" for <references> elements has the format "s-nnn". It is
important to note that "nnn" is a number, not letters, even though
the <references> appear in the back. It is the number that is one
higher than the highest top-level section number in <middle>. If
there are two or more <references>, "nnn" will include a dot as if
the <references> are a subsection of a section that is numbered
one higher than the highest top-level section number in <middle>.
o "pn" for <figure> elements always has the format "f-nnn", where
"nnn" is the figure number. For example, this would be "f-5" for
o "pn" for <iref> elements always has the format "i-ttt-nnn", where
"ttt" is the slugified item (plus a hyphen and the slugified
subitem if there is a subitem), and "nnn" is the instance of that
item/subitem pair. For example, this would be "i-foo-1" for
"<iref item='foo'>" and "i-foo-bar-1" for "<iref item='foo'
o "pn" for <table> elements always has the format "t-nnn", where
"nnn" is the table number. For example, this would be "t-5" for
o "pn" for all elements not listed above always has the format
"p-nnn-mmm", where "nnn" is the section number and "mmm" is the
relative position in the section. For example, this would be
"p-2.1.3-7" for the seventh part number in Section 2.1.3.
o "slugifiedName" always has the format "n-ttt", where "ttt" is the
text of the name after slugification. For example, this would be
"n-protocol-overview" for the name "Protocol Overview". The
actual conversions done in slugification will be specified at a
o Anchors must never overlap with any of the above. The easiest way
to assure that is to not pick an anchor name that starts with a
single letter followed by a hyphen. If an anchor does overlap
with one of the types of names above, the processing tool will
reject the document.
B.3. Attributes Controlled by the Prep Tool
Many elements in the v3 vocabulary have new attributes whose role is
to hold values generated by the prep tool. These attributes can
exist in documents that are input to the prep tool; however, any of
these attributes might be added, removed, or changed by the prep
tool. Thus, it is explicitly unsafe for a document author to include
these attributes and expect that their values will survive processing
by the prep tool.
The attributes that are controlled by the prep tool are:
o The "pn" attribute in any element -- The number for this item
within the section. The numbering is shared with other elements
of a section. The "pn" attribute is added to many block-level
elements inside sections.
o <artwork> originalSrc -- This attribute is filled with the
original value of the "src" attribute if that attribute is removed
by the prep tool.
o <figure> originalSrc -- This attribute is filled with the original
value of the "src" attribute if that attribute is removed by the
o <name> "slugifiedName" attribute -- This attribute is filled with
a "slugified" version of the text in the element. This attribute
can be used in the output formats for elements that have both
names and numbers.
o <relref> "derivedLink" attribute -- This attribute is filled with
the link that is derived from combining the URI from the reference
and the relative part that is either a copy of the "relative"
attribute or a section number derived from the "section"
o <rfc> "expiresDate" attribute -- This attribute is filled with the
date that an Internet-Draft expires. The date is in the format
o <rfc> "mode" attribute -- This attribute is filled with a string
that indicates what mode the prep tool was in when it processed
the XML, such as whether it was processing a file to become an
Internet-Draft or an RFC.
o <rfc> "scripts" attribute -- This attribute is filled with a list
of scripts needed to render this document. The list is comma-
separated, with no spaces allowed. The order is unimportant. The
names come from [UAX24]. For example, if the document has Chinese
characters in it, the value might be "Common,Latin,Han".
o <sourcecode> "originalSrc" attribute -- This attribute is filled
with the original value of the "src" attribute if that attribute
is removed by the prep tool.
o <xref> "derivedContent" attribute -- This attribute is filled in
if there is no content in the <xref> element. The value for this
attribute is based on the value in the "displayFormat" attribute.
Examples of how this value is filled can be found in
In addition, note that the contents of the <boilerplate> element are
controlled by the prep tool.