Tiddlers have a field "when" that is a space separated list of tiddler titles.
Tiddler A has "when" set to `morning [[day time]] evening`
Tidddler B has "when" set to `morning`
Tiddler C has "when" set to `[[day time]]`
Tiddler D has "when" set to `evening`
Tiddlers "morning" and "day time" have a tag "UV"
Given a string "UV" and knowing there is a field called "when", how do I write a filter that would return A,B,C, but not D?