I received an email:
I would like to identify groups of tasks using multiple variables. It seems like projects/tags are one way. Are there other, less structured methods for identification? There will be times when I want to analyze tasks and bugs across multiple variables.
"Flag For Later" currently looks like the most suitable approach to the problem.
I cannot find any docs about Phabricator's "Flag For Later" in the Phabricator Help, only as a side note on Phab vs. Bugzilla.
Text proposal:
"Flag For Later" offers marking objects (like tasks or revisions) which "you want to remember to look at later". Eight flag colors are available. Flags are personal and private. Your flagged objects are listed on https://phabricator.wikimedia.org/flag/. They can be searched for by color or object type, in contrast to tokens.