LIST/CHOICE usage

After too many years, we need to work out the issue of LIST, %LIST, CHOICE and %CHOICE.

Why do we need them, Where do we Need them and DO we need them.

A) Can we condense these four into two or even one tag?
B) If we can't condense them down, can we understand the proper usage.
C) If the code and Docs are contradicting we should hash out in a proper manner HOW we want them to work, Where they work, how they work.

Basically, this should be part of the effort to clean up the Code, Data and Docs and understand in all three areas EXACTLY what is intended, expected and will result in the usage of the tag(s)