Text decoration conformance criteria

[gsnedders]

CSS2 currently contains:

Some user agents have implemented text-decoration by propagating the decoration to the descendant elements as opposed to preserving a constant thickness and line position as described above. This was arguably allowed by the looser wording in CSS2 (1998). SVG1, CSS1-only, and CSS2 (1998)-only user agents may implement the older model and still claim conformance to this part of CSS 2. (This does not apply to UAs developed after this specification was released.)

(This text was added in 2003, in ff720b8.)

This seems… complicated.

Why do we have this? To avoid claiming we're making a backwards-incompatible change?

What does it mean for a UA to be developed after this specification was released? (What counts as released? A public working draft? A REC?) Does a simple bugfix release of a UA oblige them to change behaviour here?

[frivoal]

I suspect it's a trick needed to be able to go to REC back then. Something akin to "SHOULD do the right thing, but MAY do the legacy thing if you really have to.

No matter how justified it was back then, at this point, I think we should just drop this.

We're not really in the business of certifying UAs anyway, so we can just spec the right thing, and if for some reason some UA wants to implement CSS2.0 instead of 2.1+, that's their choice, and they don't really need special permission from the 2020 spec.

[gsnedders]

I suspect it's a trick needed to be able to go to REC back then.

Pretty certain this wasn't needed by 2011 when we did go to REC!

[svgeesus]

(Just stumbled across this while looking for something else)

The concept that UAs theoretically exist which choose to strictly conform to CSS1 or CSS 2.0 but not to any later developments can be quietly killed wherever it shows up while revising older specifications.

[gsnedders]

(Just stumbled across this while looking for something else)

The concept that UAs theoretically exist which choose to strictly conform to CSS1 or CSS 2.0 but not to any later developments can be quietly killed wherever it shows up while revising older specifications.

#5114 is related here.