A CheckReload

A_CheckReload is a code pointer used in the attack animation for the Super Shotgun.

is used to ensure that the player has at least two more shells of ammo before triggering the reload animation. If not enough are present, a transition to a different weapon is automatically performed.

Uses
The  code pointer appears in the following states in Doom's state table:

Example
The following is an example of how to set the  code pointer in a Dehacked file:

Pointer 21 (Frame 34) Codep Frame = 38

Or using BEX syntax:

[CODEPTR] Frame 1234 = CheckReload