Angle of Attack Indicator

[thist796]

So... I am trying to understand the Angle of Attack Indicator (like this one: http://starfleetsupport.com/images/Pages/Avionics2/IMG_2417L_AOA.jpg) and I cannot seem to find a straightforward explanation anywhere on the web as to how it is measured. It goes from zero to 1 and usually has a green, yellow and red areas so as to alert the pilot when he is approaching stall.
How is that number from zero to 1 calculated? My guess is that it is [Lift currently being generated]/[Max lift] but I really have no clue

Any help is MUCH MUCH MUCH appreciated!=)

[Brian_C]

My guess is that it represents the sine of the angle of attack.

[thist796]

Well, just think about it, the sine of the AOA is completely useless to the pilot. Pilots use the AOA indicator mostly for STOL, therefore this instrument must tell the pilot how close to approaching stall he is, and somehow airspeed and pressure must also go into the equation on top of the angle of attack.

[FredGarvin]

It is to my understanding that the divisions do not have any units associated with them and that the gauge needs to be calibrated on every aircraft it installed on. You've piqued my interest and I'll dig around a bit too.