Select for empty field in indexTags?

[simbun]

(11-11-2020 18:22)simoncn Wrote:  I understand the reason for the first but it might be difficult to implement. You can do this at present by using "default" to populate another tag.

I think the use case I described was the only other reason you'd want to duplicate a single tag, hence trying to squeeze it in somehow, but the proposed syntax does address a lot of the use cases and is elegant.

How about having the ability to do something like:
CLASSICAL_CATEGORY.default={CATEGORY=Classical}
So CLASSICAL_CATEGORY is only populated with the 'Classical' values from the CATEGORY tag (just trying to avoid duplicating the whole tag)?

With this and .default={"String constant"} the OP could have efficiently (without duplicating the full tag every time) achieved everything he needed without using tagUpdate or the proposed tagIndex changes (not that I'm suggesting you don't do them).

I'll stop now :-)