[css-properties-values-api] Substituting registered properties into non-registered properties

[andruud]

Issue #321 briefly mentions that this maybe isn't allowed. Example:

--registered-length: 10px;
--unregistered: 5px var(--registered-length);

Is this allowed or not?

[tabatkins]

#321 doesn't say they're not allowed; I say:

They should be able to sub into untyped properties; I imagine they'd get down-converted back into some equivalent token representation. This isn't well-specced.

So yes, definitely allowed, just not specified well. The substitution won't necessarily preserve the tokens you put in exactly, but there shouldn't be any noticeable difference unless you're doing something weird. (I'd ahve to think about it a bit to tell if there even would be a difference; I can't come up with one offhand.)