Clipping

Used to make areas of the material transparent, using a grayscale texture map where black represents complete transparency and white complete opaqueness. This is useful for quickly creating perforated materials like a mesh, since you can skip modeling the holes by hand.
Texture: Select an image. Colored images will be mapped as grayscale.
Soft Clipping (Default): Softens the contrast between complete transparency and opaqueness. The alpha channel of the image is respected, and all gray values are used to clip the material.
Hard Clipping: Increases the contrast between complete transparency and opaquness. When used in combination with the Threshold parameter, you can select which parts of the image are used to clip the material.
Threshold: Changes how the texture map is interpreted. For example, at a value of 50, 50% gray is interpreted as 50% transparent. To make a larger area of the texture transparent; increase the threshold; to make a larger area of the texture opaque, decrease the threshold. At 100, all of the texture is transparent; at 0, all of the texture is opaque.