SMW Memory Map
|$7E0000||16 bytes||Misc.||Scratch RAM, is and can be used for a big number of purposes. The general purpose is temporarily preserving a value for later use in a routine.
Of note is the following address, used in LM ASM hacks:
$7E:0003 (16-bit) - Block number from LM Map16 editor. Also used in the custom Map16 tile change routine.