I made some changes to the model(MDL). I forgot to save as .PYJ. When I open the model I get:
(TR1102) Transformer detected a model error at line xxx in file <the mdl file>
(TR0505) This action would result in two categories....
This action is cancelled.
and transformer terminates. I can bring back the on .PYJ file and do the changes again (and will not forget to save as .PYJ). But if there is another way to open the MDL file that will be great.