new xtype="phrases"

[pdowler]

For use with datatype="char" and arraysize="*" (or more restricted), this xtype would denote a | (pipe) separated list of strings.

require only single space characters within a phrase and no extraneous space adjacent to the separator (canonical form)

allow or require leading and trailing | characters? ivoa.ObsCore.pol_states has leading and trailing sepaarator to make queries work better (although a different separator).

[mbtaylor]

No strong objection, but can we have an example use case?

[mbtaylor]

... sorry, I read my github notifications in the wrong order, so answering my own question by reference to ivoa-std/VOTable#25: a list of keywords that might include entries like "dwarf galaxy". Note however that contrary to the suggestion there and here, ObsCore.pol_states uses a solidus "/" not pipe "|" character as the delimiter.

[pdowler]

I have clarified my use of pol_states as prior art for leading and trailing separator only.

[msdemlei]

...and I remark that epn-tap and regtap both use # as the separator.

Meaning: I don't like it. Let's have a proper array of variable-length strings instead of this hack and #12.