I already added a post in the "completed" section but may get wider exposure here. Following your rules: 1) I'm looking for a plug-in to create .ja archives for Trainz06 using the same algorithm as the originals do. 2) the smallest archive is about 9MB and since the file structure is known...

ok, thanks for the quick and comprehensive answer. I'll dig into the Jet pages as suggested. My immediate conclusion would be: no distribution of 3rd party .ja without official permission - right? But back to the core question...as the file-structure (unpacked) seems to be documented, how difficult ...

First of all a big Thanks! Whoever came up with this marvel is in my book a genius. I do 3d and some hex but this stuff is way beyond me. The plug-in works like a charm with Trainz06 but not 04 (no biggy - one can work around that) The question I have is: Is there a way to re-pack/compress .ja back ...