Active Duty Service Computation just means the time you started active duty.

yes they still do there are many active paratroopers on active duty still to this day.

The calling of soldiers into active duty is called MOBILIZATION.

Active duty applies to a person who is in the Air force full time, it can also apply to a reservist who is performing active duty to meet his or her yearly obligation.

Inactive duty usually applies to a member of the inactive reserve. They are not in a drill status, but could still be recalled to active duty.

Who to talk to to find out if a reservist can be recalled for active duty?