Servos - Digital vs Analog - which are compatible

[iambujo]

Hello - So I was doing some quick research to find legal servos under 4Watts when I noticed 2 types, digital and analog. As I see in the link below, the HS-322 in the KOP appears to be analog.
http://www.servocity.com/html/hs-322...rd_deluxe.html

The PWM code and wiring to the DSC creates a pulse width modulated signal to control servos as I understand it (I would have considered that a digital input, though averaged over time that creates an analog voltage). I haven't put a logic analyzer on it to see the signals yet, but I am curious the difference between analog and digital servos, and where in the FRC KOP info it defines which type of servo is compatible (if it does).

So are digital input servos compatible with FRC SW and the DSC? Or just analog servos?
http://www.servocity.com/html/hitec_servos.html

Thanks