how to convert v4 models into v5 in catia.
If you just want to convert one or two V4 models into V5 Catparts, you can just Copy & Paste Special (As Specified). This will give you a file you can modify. There are many videos on the internet that show how to do this. I found this tutorial with the step-by-step instructions: http://www.intrinsys.com/blog/quickly-convert-catia-v4-model-data-to-a-catia-v5-part
(If you have many models to convert, there is a batch utility program you can use.)