I need help with MPLAB.

Im busy with a cicuit design and at the same time im writing the code for
it. With some of the i/o lines i havent decided on what ports they should go
yet.

At the moment my code looks something to the effect of

        bsf     porta,0
        bcf     porta,1

Is there a way i can define names for porta,0 and porta,1 so that in the
code i can use the names, instead of the pin names? Then if i move something
around, all i need to do is change the name -> pin assignment and recompile,
instead of searching all the code for porta,0 etc.

Regards
   John

PS - does anyone know off-hand what the length (time) of a spark is in a
vehicle with electronic ignition ?