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General Internet Architecture Board Format The HTML format for RFCs assigns style guidance to a Cascading Style Sheet (CSS) specifically defined for the RFC Series. The embedded, default CSS as included by the RFC Editor is expected to take into account accessibility needs and to be built along a responsive design model. This document describes the requirements for the default CSS used by the RFC Editor. The class names are based on the classes defined in "HTML for RFCs" (RFC 7992).

The HTML format for RFCs, described in , assigns style guidance to a Cascading Style Sheet (CSS) specifically defined for the RFC Series. This CSS will be embedded in the published HTML, and it may be overridden by a locally defined CSS, as desired. The embedded, default CSS as included by the RFC Editor is expected to take into account accessibility needs and to be built along a responsive design model. This document describes the requirements for the default CSS used by the RFC Editor. Unless called out otherwise, any styling provided for these classes must not alter the natural language content in any visible way. Many of these classes are provided to mark the elements semantically: elements using them should simply inherit their surrounding styling. Exceptions are listed below. A class is identified for Internet-Drafts, such that certain features found only in I-Ds may be made distinct in some fashion within those drafts. The requirements will only be applied to HTML documents published by the RFC Editor as per . The details included in this document are expected to change based on experience gained in implementing the new publication toolsets. Revised documents will be published capturing those changes as the toolsets are completed. Other implementers must not expect those changes to remain backwards compatible with the details included in this document.

RFCs must be adaptable to a wide variety of devices and displays, accessible to assisted readers, and printable.

Support the display of the semantic HTML described in . Follow best practice for accessibility, as defined by the W3C's "Best Practices for Authoring HTML" . Follow best practice for mobile devices, as defined by the W3C's "Best Practices for Authoring HTML". Allow for a broad range of internationalized scripts.

The document header must be at the top of the document and include all information described in "RFC Style Guide" and "RFC Streams, Headers, and Boilerplates" .

The body of the document must conform to the following: Examples and code blocks must be in a fixed-width font ASCII art must be in a fixed-width font Reflow the text as the screen gets smaller and limit max width Block quotes must be indented Tables must allow for distinct header rows Paragraphs should include a hover-over paragraph identifier All anchor tags and URLs should be clearly distinguished as links, for example, through the use of color and/or text decoration, following appropriate accessibility standards.

Default to a sans-serif font family with broad Unicode support for web browser viewing. Default to a serif font family with broad Unicode support for printing. A fixed-width font must be used for code and artwork-tagged sections. All fonts should be publicly licensed and supported by all major web browsers.

The CSS must include support for a printer-friendly output. The print rules should be a part of the embedded style sheet; consumers of an RFC may develop their own print-specific style sheet, as desired.

Lists should provide ample whitespace between list elements for legibility unless a 'compact' class is specified (e.g., .dlCompact, .ulCompact, .olCompact).

This section describes the CSS classes that result in specific changes to the natural language content of a document. A full list of available classes, not including basic selectors, is included in Appendix A.

To be used with '.artwork' to indicate the figure should align in the center of the page flow.

To be used with '.artwork' to indicate the figure should align on the right of the page flow.

These classes will mostly be styled as part of '.artwork'. Specific classes may include '.art-ascii-art' and '.art-svg'. Artwork will be held in its own block of space, centered in the page flow, and will not float. Images should have a max width of 100% so views will scale properly across a variety of screens and devices.

Must use a mono-spaced font.

No visible changes to the natural language content; keep in default style. Note that such images are not currently allowed in RFCs.

A comment within an I-D; should be visually distinct. For I-Ds only; not for RFCs.

A comment within an I-D; should be visually distinct. For I-Ds only; not for RFCs.

A comment within an I-D; should be visually distinct. For I-Ds only; not for RFCs.

Use less spacing on a definition list than the default.

Use the standard hanging indent for a definition list; indent terms.

Do not use the standard hanging indent for a definition list; align terms and definitions along left side.

Hide from visible content.

Standard link formatting (underlined, change in color).

Hide from visible content.

Notes should be emphasized and distinct from normal paragraph text.

An RFC Editor note may be added after the standard boilerplate. It should be visually distinct to highlight final removal of the note by the RFC Editor.

Use less spacing on a numbered list than the default.

If the style attribute from the source XML contains a percent sign, a particular style setting will be required to make this setting behave like an HTML ordered list.

Pilcrows, when used as described in RFC 7992, should appear at the end of the paragraph, artwork, or sourcecode segment. They should not appear until moused-over. They should not show when printed, and they should not be selected when copied with a copy/paste function.

Should be clearly distinguished as links.

Hide from visible content.

Code examples or components should be in a fixed-width font if the human language used has an available fixed-width font option, and they should be visually distinct. If no fixed-width font is available, use the default font for that human language.

The table of contents should be clearly distinguished using an indented, ordered list with the list style set to 'none', allowing for hyperlinked, in-line dotted number notation (e.g., 1., 1.1., 1.1.1.).

No visible changes to the natural language content; keep in default style.

Use less spacing on a bulleted list than the default.

Indent from the margin of the previous paragraph.

Should be clearly distinguished as links.

Should be clearly distinguished as links.

Security vulnerabilities can be introduced through the CSS, as with CSS injection attacks . In order to avoid or mitigate any attack vectors here, the CSS used must comply with the current CSS Specifications from the W3C.

W3C &RFC7841; &RFC7322; The canonical format for the RFC Series has been plain-text, ASCII- encoded for several decades. After extensive community discussion and debate, the RFC Editor will be transitioning to XML as the canonical format using the XML2RFC version 3 vocabulary. Different publication formats will be rendered from that base document. These changes are intended to increase the usability of the RFC Series by offering documents that match the needs of a wider variety of stakeholders. With these changes, however, comes an increase in complexity for authors, consumers, and the publisher of RFCs. This document serves as the framework that describes the problems being solved and summarizes the many documents that capture the specific requirements for each aspect of the change in format. In order to meet the evolving needs of the Internet community, the format for RFCs is changing from a plain-text, ASCII-only format to a canonical XML format that will in turn be rendered into several publication formats. This document defines the HTML format that will be rendered for an RFC or Internet-Draft.

This section lists all the CSS classes. Except for those also listed in , none of these result in specific changes to the natural language content of a document. .adr .alignCenter .alignRight .annotation .artwork .art-ascii-art .art-logo .art-svg .ascii .author .authors .bcp14 .center .city .compact .country-name .cref .crefAnchor .crefSource .dlCompact .dlHanging .dlParallel .docInfo .ears .email .eref .finalized .fn .index .indexChar .indexIndex .indexItem .indexPrimary .indexSubItem .initial .iref .irefItem .irefRefs .irefSubItem .label .left .locality .nameRole .note .rfcEditorRemove .olCompact .olPercent .org .organization .pilcrow .postal-code .published .refContent .refDate .refInstance .refTitle .reference .region .relref .rendered .RFC .rfcEditorRemove .right .role .selfRef .series .seriesInfo .sourcecode .lang-* .street-address .status .street-address .surname .tel .toc .type .ulCompact .ulEmpty .url .workgroup .xref .vcard

The IAB members at the time this memo was approved were (in alphabetical order): Jari Arkko Ralph Droms Ted Hardie Joe Hildebrand Russ Housley Lee Howard Erik Nordmark Robert Sparks Andrew Sullivan Dave Thaler Martin Thomson Brian Trammell Suzanne Woolf

With many thanks to the RFC Format Design Team for their efforts in making this transition successful: Nevil Brownlee (ISE), Tony Hansen, Joe Hildebrand, Paul Hoffman, Ted Lemon, Julian Reschke, Adam Roach, Alice Russo, Robert Sparks (Tools Team liaison), and Dave Thaler. Additional thanks to Arlen Johnson of Spherical Cow Group, LLC, for his assistance in clarifying the requirements in more CSS-designer-friendly language.