Quote - z buffer is a photoshop thing AFAIK. Looks like a wings issue to me. That hole mat buisness is is none sense. If it's a hole why would it need a mat?

with mat you mean material?

you can create holes in the geometry or in the material

If in the material, something like an alpha channel can be used to indicate opacity. Fully transparent is equivalent to a hole.

except, it could still show specular highlights or reflections, even refraction. Tricky tricky