Is this matter's what wire you conect when you have light fixture with no colored wires.

The fixture may have no colored wires but does your supply? Most folks don't seem to care but I always install and then test the base to insure the hot spot is the small tab down inside the bulb socket. Got to be some code out there but most folks just hook black and then white to either wire.

The code is 410.23 of the 2005 NEC Polarization of Luminaires (fixtures). Neutral is required to be connected to the shell.

Check the wire for a rib along it's length. You may not be able to see it but you'll feel it if it's there. That will be the neutral wire.