asterisk users - Dec 2003 - PRIMARY=wcfxo?

I was wondering is anyone can tell more about the following lines in the
zaptel makefile:

#PRIMARY=wcfxsusb
PRIMARY=torisa
#PRIMARY=wcfxo

I am using 2 zaptel X100P's, and wondering if I should change this in my
Makefile to:

#PRIMARY=torisa
PRIMARY=wcfxo

Just a thought.  any info is appreciated.