I have looked at several sources for information on using the Carry and Zero flags to compare quantities.  For example, if I use

sublw         L

and the Z flag =1 it can safely be assumed that W=L .  If the Z flag =0, it can safely be assumed that W<>L.  If the Carry flag =0 it can be safely assumed that W>L, and finally if the Carry flag = 1, it can be safely assumed that W <=L .

However, things seem to get weird around 0, assume that W=0, after the following is executed, I think that Carry flag should be zero. (maybe its not, but I would like to know why)

sublw       15

According to the PIC16F84 data sheet, the sublw subtracts by using two complement addition.  Therefore 15-0 = 15 + (Two's Complement of 0) = 15 + (b'11111111' + b'1') = 15 + 0 = 15 which should not set the Carry Flag.  Carry Flag = 0 is supposed to imply that W > L, but W=0 and L=15 , and 0 is NOT greater than 15.

I am still not completely comfortable with two's complement stuff so I could be completely wrong.  Any help would be greatly appreciated.  Thank You.