Epson GT-6500 EN - Manual (Page 142)

Halftoning mode C (net-screen)
The image is processed so that it is represented similar to the net
screen used in newspaper printing. The gradations of the tones are
represented by clusters of different numbers of dots.
Dither modes A, B, C, and D (fixed pattern dithering)
These modes have the following dither patterns.
3-48 Command Reference