The most recent charter says this about incubation and the Web Platform Incubator Community Group:

“The CSS WG may incubate speculative new work in the WICG, and may adopt promising CSS work developed in WICG, provided that RF patent commitments are in place for such work.”

We will some times take new work from WICG, some times start new work in the WICG, and other times start new work in the CSSWG. There are existing 'incubation' steps in the CSSWG (pre-WD documents, level+1 specs, author/user surveys) that we should continue to use and socialize with WICG.

The venue for new work should be evaluated based on open criteria. The lists below are suggestions on what those criteria could be. The items are merely meant to inform a decision on the venue, not to provide a scoring mechanism. Some of the items will be more or less important depending on the feature at hand.

Considerations for incubation within CSSWG

1. The feature is an extension of an already-existing feature
2. The feature was worked on previously but postponed to simplify current work
3. Clear signals from users/authors exist
4. The feature is codifying/easing current widespread practice
5. The feature has two or more browsers interested in starting work
6. There is consensus on the design shape
7. The people needed for the work are already WG participants
8. The people doing the work want to start in the CSSWG

Considerations for incubation outside of the CSSWG

1. The feature was worked on previously but abandoned due to objections
2. No clear signals or mixed signals from users/authors
3. The feature has zero or one browsers interested in starting work
4. Competing design shapes have been proposed
5. Expertise from outside the WG is needed
6. The people doing the work want to start in the WICG
7. The people interested in the work are not WG participants