why mdl and pyi in batch file since it was build already?

[venkys4u]

hi friends.. since im under training i dont have deep knowledge abt cognos

actually i have a doubt using mdl and pyj in transformer.. i feel transformer is used for creating model and custom view of dimension, power cube etc
but since mdl was created already then y we should to batch file for
building dimension in automation.. plz make this concept clear to me
friends.. when i was trying with batch file it was saying cogtr.exe is not recognized as an internal r external command, operable program or batch file


thanks in advance
venkys4u