Httempang

httempang holds the number of the sprite's previous palette (if the sprite is not a player). The sprite's palette is set to this number when the getlastpal command is used. Note that the previous pal is stored in httempang only when the spritepal command is used.

Given the name of this member, it seems likely that it was originally intended to store an angle.

See pal for more information about palette swaps.