lists what? phrases?
Phrases are just bits of text that are in templates. The reasaon for using a phrase instead of the text itself is for easier conversion for other languages. That way they just add another languange phrase set instead of maintaing a whole different set of phrases...
Not all hacks use phrases, some people are nice and try to be consistent with vB3 coding guidelines so they use phrases, but it's not a necessity for hacks.