[Legends of Athas] The Order Adept prestige class?

Rules 3rd Edition D&D or Pathfinder
1

I was reading the Expanded Psionics Handbook and I seem to recall that psions stop getting powers and psionic points once they hit manifester level 20. I don’t recall if there were other class features that top out at 20th level, requiring epic feats to progress. (Something to do with the class already has a lot of versatility, s

The prestige class requires 9th level powers, so minimum of 17th level. The class provides +6 levels of the base features (manifester level, psionic points, etc.), plus +3 of even more stripped down features (+1 every three levels).

What exactly does that give the character?

I’m asking partially for this prestige class, but also because of all the builds for the advanced beings (mostly dragons) I’ve seen posted.

Edit: Okay, now that I’m looking at my books, epic psions can:

Spend points up to their manifester level (e.g., a 25th level psion can spend 25 points on a mind thrust).

Gain 2 new powers for every epic level. (Probably not included in the “+1 manifester level” stuff.)

Increase their psicrystal’s power. (Another one probably skipped.)

They cannot get more psionic points after 20th level, except by stat increases, unless they use a feat.

2

Right, just like wizards and clerics don’t get further spell slots at epic levels.

3

Well technically you could, but not by progressing in your base psionic class. Just like there are some epic level Wizard/Sorcerers like the Simbul in Forgotten Realms, you could be a Wilder/Psion or some other such but at the expense of your base class powers not progressing above 20th.