grid shader

[the pang]

I have been trying to use the grid shader and am confused about the settings. What exactly is being specified with the color height and width? How does this differ from the grid size? If I set the color and the transparency numbers the same will I get a grid with solid lines and a transparent background?

When I set the size at the bottom of the create/edit texture dialoge box what am I setting? Is the width like for images or something else?

I've been trying different things but what I want is a grid with 6"x6" holes and 1/2" lines. I know that I can make a grid and model it but the shader should be less memory intensive.

Thanks