Final Opacity

This feature lets you control the opacity after all the calculations in the shader. It's performed after halftone transparency and before the cutout is calculated. So you can use this to have a more fine grain control over what parts of the material are being shown.

You can specify the opacity mask by using the mask system and providing a mask to read from. The mask will be interpreted as the opacity mask, with 1 (white) being opaque and 0 (black) being transparent.

More information about the mask system can be found here