Hello everyone!

I came to Hong Kong, I like 3D, but my English is not good, and now I am using Google Translate! Please forgive me!

I'm having problems in MAYA do not understand! In the "Orient Joint Options"!
I understand that "Premary Axis"! But "Secondary Axis" & "Secondary Axis World Orientation" I do not understand! Can you teach me?

Thank you for help