Reserve Categories allow you to preconfigure common Reserve Availability Periods (RAP) assigned by your airline. They can be thought of like a Payroll Category which sets certain parameters so you don't have to configure each one as you enter it. This allows for quick entry of RAPs into your schedule once configured.
APDL has three default Reserve Categories: Airport/Standby Reserve, Long Call Reserve, and Short Call Reserve. You should configure each one of these before use to ensure they are useful for your airline, but you can also create your own custom Reserve Categories. For example, if your airline has two common Short Call Reserve assignments, one in the morning that starts at 0500 and one in the afternoon that starts at 1300, you could create a specific Reserve Category for each. Go to the Manual Entries page for more details on inserting Reserve Availability Periods into your schedule.