If tasks had keywords sub-modules could be named in projects, as currently a submodule is being listed as a project.
This is a simple approach to allow more versatility, allowing tags such as MODULE::STATCOUNTER. or TESTING, or PRODUCTION.
Filtering by tags would be possible too.
NB, this is my first suggestion critiques welcome
@pearlcode: I'd say that keywords, tags, <random-other-term> are projects in Phabricator. You can define any kind of projects as "keywords" (e.g. by using a specific icon and a color). Filtering by projects is already possible.
But if you are actually after subproject functionality and expressing hierarchy between projects (instead of "keywords" which might be just one possible solution to some actual problem and the latter should be covered in task descriptions), please feel very free to merge this task into T3670.
So I propose to close this task.