So there have been a lot of posts in this community about two-weapon fighting (aha: specifically, this one), and I'm still not certain I understand it correctly.

So there's the core rules about TWF, and then there are the feats.

Here's how I understand it: If you have a rapier and a dagger, and you're a first-level fighter, then:

• you can attack with either the rapier *or* the dagger at +1 (which is equal to your BAB)


• you can attack with the rapier *and* the dagger at -3 (rapier) and -7 (dagger). (The penalties are less than they would be with two rapiers, because the dagger is a light weapon.)


• If you have the Two-Weapon Fighting feat, you can attack with both the rapier and the dagger at -1 each (again, less of a penalty because the dagger is light).
  

Here's my main question: Does that extra attack from fighting with two weapons only trigger if you take a full attack action (i.e. a full-round action), or can you do it as part of one single standard action?

Let's say our fighter is now 12th level, with TWF, ITWF, and GTWF. This means he gets 3 extra attacks with his off weapon per [action - full or standard?]. His BAB is +12/+7/+2.

If TWF can be done as a part of a standard attack action, then he has a couple basic options for his round:

(a) Attack at +10/+5/+0 with his rapier and +10/+5/+0 with his dagger. Full-round action.
(b) Attack at +10 with his rapier and +10/+5/+0 with his dagger. Standard action. Then he can move 30 feet.

If TWF can only be done as part of a full-round action (full attack action), then he can either do option (a) from above or

(c) Attack at +10 with his rapier (standard action) and move 30 feet.

So. Which one is it? (And is this explained in the SRD anywhere? I keep feeling like I've missed it somewhere obvious.)

Thanks!