Select for empty field in indexTags?

[simbun]

(10-11-2020 10:46)simoncn Wrote:  A better solution would be to add support in indexTags for something like:

Category=Classical:Classical Library^etc:any_name_you_want^:Default

If you're going to look at this, would be good to consider:

• Is there some way this syntax could also allow you to use Category itself as a simple index? I may want one value as a quick filter, but may not want to create as many filters as there are values for the rest.
• Rather than addressing the missing value option here in the automatic selection syntax, would it not be better to address it as .default('String constant'). I think this has been requested before, and it would then work as a simple index too.