On 12/10/2011, at 9:08 PM, Joseph Wright wrote:

> Well, both 'once' and 'first' assume you know something about the
> 'order' of the variable (otherwise 'once' could mean anything). I'd
> agree that 'first' is probably better overall: make the change?

False alarm -- such changes are too disruptive to expl3 users (including us) and we're trying hard to keep expl3 as stable as possible in this regard.

Cheers,
-- Will