I think i figured it out, but i'm still confused ...

When i compile :
Code:
TRISB   = %00111100                                      'Set TRIS register input's & output's
PORTB   = %00000000                                      'Set all digital low

SDA     var PORTB.0                                      'I2C DATA pin
SCL     var PORTB.1                                      'I2C CLOCK pin
It compiles, without any errors !
How ?