Sprites are associated with Frame definitions. Each frame of
a sprite should look like what a Thing is doing during that
frame. The frame's definition refers to a sprite number and
a sprite subnumber. You can make a frame render the sprite
with full brightness by adding 32,768 to the sprite subnumber.
Frame 217 (Shotguy Far Attack 1)
Sprite number = 30 #SPOS
Sprite subnumber = 4 #E
Frame 218 (Shotguy Far Attack 2)
Sprite number = 30 #SPOS
Sprite subnumber = 32773 #F Bright
The original Doom engine and Chocolate Doom tend to only load sprite filenames which existed for the original sprite. For example, Chocolate Doom only loads sprite files named BOSS with frames A through O. Despite this limitation, these engines appear to load any and all rotations available. For instance, Chocolate Doom will load 'bosfa0' or 'bosfa1' or 'bossa2a8' as sprite subnumber 0 for the BOSF sprite.
╔══╤══╦══╤══╦══╤══╦══╤══╦══╤══╦══╤══╗ ║ 0│A ║ 5│F ║10│K ║15│P ║20│U ║25│Z ║ ╠══╪══╬══╪══╬══╪══╬══╪══╬══╪══╬══╪══╣ ║ 1│B ║ 6│G ║11│L ║16│Q ║21│V ║26│[ ║ ╠══╪══╬══╪══╬══╪══╬══╪══╬══╪══╬══╪══╣ ║ 2│C ║ 7│H ║12│M ║17│R ║22│W ║27│/ ║ ╠══╪══╬══╪══╬══╪══╬══╪══╬══╪══╬══╪══╣ ║ 3│D ║ 8│I ║13│N ║18│S ║23│X ║28│] ║ ╠══╪══╬══╪══╬══╪══╬══╪══╬══╪══╣ │ ║ ║ 4│E ║ 9│J ║14│O ║19│T ║24│Y ║ │ ║ ╚══╧══╩══╧══╩══╧══╩══╧══╩══╧══╩══╧══╝