The Passes panel

Control

Effect

Material ID (checkbox)

Enables the pass on this view layer. Assigns colours and registers the AOV.

Pass Name

The AOV's name, and the exported file's name. Defaults to MaterialID.

Scope

Scene Materials covers materials used by objects in this scene; All Materials covers every material in the file.

Palette

Stable or Max Contrast — see section 8.

Seed

Reshuffles the palette.

If other view layers have the pass on, they are listed at the bottom of the panel.