Psion: Explain it to me

[Humble Master]

I have the old 3.0 Psionic Handbook and have thus been using the 3.0 Psion. However I want to switch to the 3.5 Psion but some of the stuff is unclear to me.
Basically which powers can I learn? I know I can pick from the Psion list and my chosen Domain but this line on the SRD confuses me.
"You can choose powers from disciplines other than your own if they are not on a restricted discipline list."
What is a restricted discipline?
Also what does it mean by
"You cannot choose powers from restricted discipline lists other than your own discipline list."
Does that mean that if a power is on a discipline list I can't learn it even if it is on the Psion list?

Could someone please explain the intricacies of how Psions learn their powers.

[Flickerdart]

Every psion must specialize in a discipline. Each discipline has a list of unique powers (http://www.d20srd.org/srd/psionic/powerList.htm#psionDisciplinePowers) that only psions that specialize in it can learn. So a Telepath could not learn Metamorphosis (which is an Egoist-exclusive power) but could learn Body Adjustment, even though both powers are in the Psychometabolism discipline.

[Yora]

Powers that are both on the general Psion list and also on one of the six disciple lists, usually work somewhat different for the specialist psions.
You can learn every power on the general psion list, plus the powers from your chosen discipline list. If it is not on either list, you can not learn it.

Unless you take the Expanded Knowledge feat. This feat adds an additional power that you learn, and this power can also be from any other power lists, to which you normally do not have access.

[Humble Master]

Thank you Flickerdart and Yora, your comments have been most useful.
I have one more question. Are their any rules for making Psionic traps? For instance a Auto Reset Deja Vu trap to make someone constantly repeat what they were doing when they got hit by the trap.

[Flickerdart]

Thank you Flickerdart and Yora, your comments have been most useful.
I have one more question. Are their any rules for making Psionic traps? For instance a Auto Reset Deja Vu trap to make someone constantly repeat what they were doing when they got hit by the trap.
I don't think there are explicitly, but psionic-magic transparency covers items, and the guidelines for creating psionic items explicitly refer to the custom magic item guidelines for costs. It wouldn't be at all far-fetched to suggest that psionic traps are likewise created and priced the same way as magic traps.

[Cicciograna]

Thank you Flickerdart and Yora, your comments have been most useful.
I have one more question. Are their any rules for making Psionic traps? For instance a Auto Reset Deja Vu trap to make someone constantly repeat what they were doing when they got hit by the trap.

Dungeonscape has rules to make psionic traps IIRC.

EDIT: yep, page 137 of the book.