Carson Car Shops

In most everything we do with the art files or certain file pictures there is that .TGA version.
I understand what the filename is and also the .JPG filename.
But why is it necessary to have the TGA in place and the JPG cannot be substituted ?
Is it a Gmax requirement ?

I believe it's game related. TGA is a more compressed format making it easier for the code to read it. I don't recall ever modding any other game with all formats as does Trainz. (TGA, JPG, BMP)

I think it's the other way round. .jpg's require uncompressing in-game which adds to rendering time. When you save a texture as a compressed .tga is when you get problems. Gmax doesn't care what you use.
But then again, I could be wrong.
Norm