CSS3 Development Status – An Explanation of W3C Maturity Levels

W3C assign each of their specifications a maturity level, which shows their current place in the development process. Those which apply to the CSS3 modules are shown below, along with an explanation of their meaning.

W3C Recommendation (REC)

A W3C Recommendation is a specification or set of guidelines that, after extensive consensus-building, has received the endorsement of W3C Members and the Director. W3C recommends the wide deployment of its Recommendations. Note: W3C Recommendations are similar to the standards published by other organizations.

Proposed Recommendation (PR)

A Proposed Recommendation is a mature technical report that, after wide review for technical soundness and implementability, W3C has sent to the W3C Advisory Committee for final endorsement.

Candidate Recommendation (CR)

A Candidate Recommendation is a document that W3C believes has been widely reviewed and satisfies the Working Group’s technical requirements. W3C publishes a Candidate Recommendation to gather implementation experience.

Last Call (LC)

In general, a Last Call announcement is a signal that the Working Group is planning to advance the technical report to later maturity levels. The Last Call announcement specifies the deadline for review comments and also signals that the Working Group believes that it has satisfied its relevant technical requirements (e.g., of the charter or requirements document) in the Working Draft.

Working Draft (WD)

A Working Draft is a document that W3C has published for review by the community, including W3C Members, the public, and other technical organizations. Some, but not all, Working Drafts are meant to advance to Recommendation.


Not technically a W3C Maturity Level. Css3.info has marked those modules as ‘announced’ which have been announced, but for which no working draft or other tehcnical information is yet available. CSS3.info will continue to follow the progress of these modules and update the table as and when details become available.

Further details of the W3C Maturiy Levels can be found on their website:


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