Fancy that, I was just looking at some AA stuff today
Check out table: altadv_vars, there are 2 columns in this table - prereq_skill, prereq_minpoints. I believe those are the 2 values that check what previous AA's are required (and how many points per) before you can spend any on the current AA.
I think you're asking about character level - like some AAs were not available if you weren't level 63+, etc, right? That, I do not see in a table. It would lead me to believe the Emu does not have that requirement, but I could be wrong.
(I just did a quick pass over AA.cpp, and I do not see anywhere that character level is being compared, but that does not mean it is not cleverly disguised as something glaringly obvious - have yourself a look see).