ID functionality in PROC MEANS

In real world, there are two kinds of data: numerical and categorical.
Regardingly, in SAS world there are two basic tools: PROC MEANS and PROC FREQ.

PROC MEANS is commonly used to summarize numerical data.
Additionaly, it can provide ID functionality as follows:

1. ID statement + IDMIN and PRINTIDVARS options in PROC statement
2. MAXID and MINID options in OUTPUT statement
3. IDGROUP option in OUTPUT statement

All work only for output dataset except PRINTIDVARS, which is for the printed output.
As far as output dataset is concerned, the ID functionality scope is #1 < #2 < #3.
That means IDGROUP is most powerful, like TopN/BottomN, obs, last etc.

Correspondingly, IDGROUP is most complex.