Phantasy Star Gen2 .DAT files

Hello all, long time no see.

I stumbled over my favorite game of all time again when a complete translation was finally made public, and this version of the game is just so pretty, so I'm totally going to rip it.

I'm already hitting a stumbling block, though.  The .DAT files can't be decompressed the same way I usually do, and looking at it, there doesn't seem to be a header on any of them.  If someone can give me a clue as to where to start with this, I'd be grateful.

Here's the .DAT for the battle files.  Any help would be appreciated.