JUMP contains an iMUSE jump hook, signifying a position in the music where a jump could occur - for loops, jumps to transitions etc. Such a jump will only occur if the hooks HookID corresponds to the HookID set by the SCUMM script.

"JUMP"	dword	Block identifier
dwSize	dword	Size in bytes (BE)
dwPosition	dword	Hook position.
dwDestination	dword	Jump destination byte offset.
dwHookID	dword	Hook ID.
dwUnknown	dword	Unknown.