What is active point

More info needed.

Hi

when i am using easyGPS, it ask me where to set the active point.
As i understood, it is the location of the active direction, BUT what more, i don't know.

thanks

I can only find references to Active Point and how to set it on the following sites:

http://www.expertgps.com/help/cmd-set-active-point.asp

http://www.easygps.com/help/cmd-set-active-point.asp