Unity Script Reference:
Legacy Documentation: Version 4.3.0
BlendMode
Description

Blend mode for controlling the blending.

The blend mode is set separately for source and destination, and it controls the blend factor of each component going into the blend eqquation. It is also possible to set the blend mode for color and alpha components separately. Note: the blend modes are ignored if logical blend operations are in use.
Variables
Zero Blend factor is (0, 0, 0, 0).
One Blend factor is (1, 1, 1, 1).
DstColor Blend factor is (Rd, Gd, Bd, Ad).
SrcColor Blend factor is (Rs, Gs, Bs, As).
OneMinusDstColor Blend factor is (1 - Rd, 1 - Gd, 1 - Bd, 1 - Ad).
SrcAlpha Blend factor is (As, As, As, As).
OneMinusSrcColor Blend factor is (1 - Rs, 1 - Gs, 1 - Bs, 1 - As).
DstAlpha Blend factor is (Ad, Ad, Ad, Ad).
OneMinusDstAlpha Blend factor is (1 - Ad, 1 - Ad, 1 - Ad, 1 - Ad).
SrcAlphaSaturate Blend factor is (f, f, f, 1); where f = min(As, 1 - Ad).
OneMinusSrcAlpha Blend factor is (1 - As, 1 - As, 1 - As, 1 - As).