I offered this once before:
AC-1
Non-inductive or slightly inductive loads (resistive loads) such as resistance furnaces.
AC-2
Slip-ring motors, starting, plugging (stopping or reversing the motor while running).
AC-3
Squirrel cage (AC Induction) motors, starting, switching off motor while running.
AC-4
Squirrel cage (AC Induction) motors, plugging, jogging, inching.
DC-1
Non-inductive or slightly inductive loads (resistive loads) such as resistance furnaces.
DC-2
Shunt motors, starting, switching off motors while running.
DC-3
Shunt motors, starting, plugging, jogging, inching.
DC-4
Series motors, starting, switching off motors while running.
DC-5
Series motors, starting, plugging, jogging, inching.
I failed to reply then about AC23 but here is a link that offers info:
http://www.galco.com/circuit/Switches.htm