East-Sider,
You will be informed that you will see ONE light at a time, and that each light will be either RED, GREEN, WHITE, YELLOW or BLUE (I think).
You will sit opposite a mirror and the light is projected from the lantern onto the mirror. The effective distance is either 5 or 6 metres for the Beynes test, the other distance being applied to the H-W test.
The test is conducted in a darkened room, lit artificially with a lamp which is projected onto the wall at the side of the mirror.
HTH and Good Luck.
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