Format of Mask layer

I can never remember. How should the mask layer be formatted? I hope I can describe this clearly:

  1. As a “negative” mask where I put little circles where I don’t want mask?
  2. As a positive mask, formatted like a copper mask where I have an entity everywhere I want mask and leave the openings blank? i.e., have a large rectangle the size of the board and create holes where I want the openings to be.

Hello @KeithB

Positive is anything drawn on that layer represents material example: copper, solder paste and ink
Negative is anything drawn on that layer represents absence of material example: opening in solder mask.

So the mask layers are negative masks?


Correct the solder mask layer is considered a negative layer, the gerber shows where the material is going to be removed.

Thanks! Hopefully it will stick in my brain this time!