This site contains information about the alphafiles
In the Alpha the ADTs and the WDT were just one big file with this structure:
'MVER': See the new files
'MDNM': Filenames Doodads
'MONM': Filenames WMOS
'MCIN': 256 Entries, so a 16*16 Chunkmap
'MTEX': See the new files
'MCNK': contains Heightmap(?),MCLY and MCRF
Againg one big file: This is, what now is stored in the Rootfile
And this is what now is stored in the Groupfiles
repeatet n-times, where n is the number of what now is groupfiles.
The old Model-Format, it's a lightly modified WC3-Modelformat.