🚲 A preprocessor for anyone writing specifications that converts source files into actual specs.
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Bikeshed, a spec preprocessor

Bikeshed is a pre-processor for spec documents, turning a source document (containing only the actual spec content, plus several shorthands for linking to terms and other things) into a final spec document, with appropriate boilerplate, bibliography, indexes, etc all filled in. It's currently used on nearly all specs in the CSSWG, as well as various specs in the FXTF, SVGWG, WebAppSecurity, WHATWG, and elsewhere!

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The processor can be easily installed and run locally (requiring no network access unless you're updating), or accessed as a CGI without any installation at all: https://api.csswg.org/bikeshed/

A short overview of some of Bikeshed's features:

Documentation Sections

The full Bikeshed documentation is generated by Bikeshed and accessible here.

Note About Fatal Errors

Bikeshed generates "fatal errors" for lots of things that it wants you to fix, but generally recovers gracefully from them anyway. If you're getting a fatal error, but don't have time to fix it and just need a spec right now, you can force Bikeshed to generate anyway with the -f flag, like: bikeshed -f spec.

This is also sometimes useful when converting a spec to Bikeshed for the first time, so you can see all the errors at once and fix them in whatever order is easiest, rather than having to deal with them one-by-one with no idea when they'll end. (You may also want to silence the warnings in this case, to reduce visual noise until you've gotten it at least building successfully. Use bikeshed -qf spec.)

Bikeshed File Extension

The preferred file extensions for Bikeshed source files is bs, like index.bs. Bikeshed will automatically recognize *.bs files in the folder it's run in, and assume that you want an output file of the same name with a .html extension. The repository also contains a syntax highlighting script for Bikeshed source files.

(Bikeshed also recognizes files with *.src.html for backwards compatibility with older CSS specs, though most such specs have switched their source file extensions to .bs now. Using .src.html in most text editors will display the file with HTML source formatting, which isn't generally what you want.)


This document and all associated files in the github project are licensed under CC0 . This means you can reuse, remix, or otherwise appropriate this project for your own use without restriction. (The actual legal meaning can be found at the above link.) Don't ask me for permission to use any part of this project, just use it. I would appreciate attribution, but that is not required by the license.