Quote - you can use the unmodified transparency map on the specular value input to kill the reflections where you want a hole, but that's also an example of what can catch you out. What you're doing with that specular value is multiplying the numeric value by the equivalent value of the texturemap. Black is zero, so the black gives you zero reflection. I suppose we could call it an opacity map, but there's no point in changing now.

I didn't know that. Thanks for the tip :)

"It is good to see ourselves as others see us. Try as we may, we are never
able to know ourselves fully as we are, especially the evil side of us.
This we can do only if we are not angry with our critics but will take in good
heart whatever they might have to say." - Ghandi