Why do some models only work in certain mods?

[Col7777]

Thanks Sniper,
I understand you answer, I have noticed in the files a sub/ship relates to another model.
I figured too that the files were shared, they do that in flight sim in a lot of cases, I don't know what program to use to open those files so I could perhaps see what is needed etc, so in some cases I did copy some files from a playable vessel to hopefully get the non playable to work but I drew a blank.

I may have been close and not realised lol. I said in one of my posts, I have downloaded some 'Playable' not 'Human Playable' ships and they look really good models but after spending many hours tweaking and renaming files I gave up.

Col.