Psionic Secondary Discipline Help

[Coolplayer]

In what OFFICIAL WoTC book is the rules on taking up a secondary discipline for Psions (if any)?

In the Epic Level Handbook (pg 22, line 6 from the top right hand column) it states "...primary discipline." The fact that it states 'primary' implies a secondary.

 

[Dandu]

There are several disciplines. At creation, a psion chooses one of them as his primary. The others are all secondary.

Far as I can tell.

 

[Bacris]

There are several disciplines. At creation, a psion chooses one of them as his primary. The others are all secondary.

Far as I can tell.

This is accurate.

Additionally, it should be noted the rules for the Epic Level Handbook were written before the Expanded Psionics Handbook were published and instead work off the 3.0 Psionics Handbook, which was drastically different in rules.

But, a psion chooses a primary discipline. The other 5 are all secondary. There's not a single secondary discipline (they all are secondary disciplines), nor are there any tertiary or barred disciplines.