I've created a set of macros in an attempt to produce mapping files that can be read and edited by humans. Of course, program support for these is currently lacking, but I may do something about that in the future. In order to use these you will have to define a SonicMappingsVer constant equal to 1, 2 or 3 depending on the game you're editing, and include SpritePiece.asm. You can find the asm file containing the macros here, a sample converted file here, and a converter program (with SpritePiece.asm file) here. About the "spritePiece2P" macro: that's only needed if you're editing Sonic 2 and your sprites use the same mappings but a different art tile in 2P mode, otherwise the 2P data will be automatically calculated. Edit: updated to use "mappingsTable"/"mappingsTableEntry" macros instead of "dc.w piece-main" statements.