Full syntax :
    #SpriteFile name
    
This defines a Spritefile where the Sprite command will look for a sprite. It will first be loaded when a Sprite command is encountered, so it can be defined put in a modules !Configure file. When loaded the entire file is loaded, not just the one used sprite..

From StrongHelp 2.74, sprites may have mode sufficies as with *iconsprites. For example, a page may have a Sprites22 file and a Sprites file. In a hi res mode, the 22 file is used first - if this doesn't exist, the Sprites file is used. The file is reloaded on a mode change.

Example:
#Spritefile !Sprites
#sprite c,f mysprite