Action point categories:
General purpose
Attack
Casting
Movement

Point sources:
Each round, action points come from these sources.
General Purpose:  10 + 4d4 + Initiative modifier
Attack:  Base attack modifier
Casting:  Casting modifier
Movement:  Dex mod

Using points:
Every action must use at least one GP point.
An action can use points from the GP category and the category of its type.
(An attack requiring 5 action points can draw 1 from GP and 4 from Attack to reach the total of 5)

Initiative conversion from D&D 3.5/Pathfinder:
Init = Dex mod + (class features / 2) + (feat bonuses / 2) + (spell bonuses / 4)

Casting modifier:  Equivalent to the base attack progression, but for casting classes.
Wizards, Sorcerers, and other classes that improve spells per day in the same fashion are considered full casters.
Rangers, Bards, and other classes that improve spells per day in the same fashion are considered 3/4 casters.
Classes with a worse progression are considered half casters.
casting modifier = casting type * level

Action cost conversion from D&D 3.5/Pathfinder:
General guidelines:
Free/swift/immediate action -> 1 action point
Move action -> 10 action points
Standard action -> 15 action points
Full round action -> 20 action points

Specifics:
Attacking:
Light weapon -> 5 action points
One-handed weapon -> 10 action points
Two-handed weapon -> 15 action points

Casting:
Use casting times and general guidelines for conversion.

Movement:
Each point used moves the character 1/10 of their speed.

Haste:
+2 Attack points
+2 Casting points (only for casters)
+10 Movement points


Attacks of Opportunity:
Unhandled because they're ridiculously complex and nail people's feet to the floor.