A few questions about OpenCOLLADA exporter for Maya

I’m writing the documentation of my game engine. The chapter I’m currently working on is about OpenCOLLADA. Unfortunately, its exporter for Maya has not a documentation at all. So could you please give me a few information about the following option:
-Curve Constrain

I’ll put my engine’s SDK on the internet for free. Its official website is www.vandaengine.com
Best Regards,