Need Help! Timing belts.. what configuration?

Hi guys, im finishing my first CNC machine 1000mm x 900mm cutting area, im panning to build a new machine using timing belts, the size that i want is close to 800x800mm.

I was reading a some post abt timing belts but dont found any post that explain me the diferents ways to mount the motor/bear/timing belts, i see some small machines where ppl place the motor at the corner of the belts, others where ppl use the motor in the middle of the belt (using just one side of the belt,

i want to know if someone can point me to some doc that explain the diferents ways to use the belts.

Regards