There are three kinds of light distribution curves, see Figure 1.
8.14.2.2.2 Type values
Type
Description
TYPE_A
Type A is basically not used. For completeness the Type A Photometry equals the Type B rotated 90° around the Z-Axis counter clockwise.
TYPE_B
Type B is sometimes used for floodlights. The B-Plane System has a horizontal axis. B-Angles are valid from -180° to +180° with B 0° at the bottom and B180°/B-180° at the top, β-Angles are valid from -90° to +90°.
Figure 8.14.2.2.A
TYPE_C
Type C is the recommended standard system. The C-Plane system equals a globe with a vertical axis. C-Angles are valid from 0° to 360°, γ-Angles are valid from 0° (south pole) to 180° (north pole).