Program zero for 4th & 5th axis

[emsee]

I'm working on my first 4th & 5th axis project using Mastercam. I have no problem of programming but am confusing about the program zero.
I understand that I can define a corner of the workpiece as program zero for a 3 axis program. But for 4th and 5th axis, the part will be rotated around and so the program zero. My question is:

Is there a practical and safe method to define program zero for 4th & 5th axis?
Please, explain.

Or Mastercam will automatically compensate for the rotation of the program zero no matter where I define it?

[Ashish B]

DYNAMIC FIXTURE OFFSET is used in 4th & 5th axis machining centre.

You can get valueable info if you browse web for it.

Thanks