All information here is to my best knowledge, is is not proven by any official reference manual by Microsoft or Terminal Reality.

ACT files are files containing an indexed list of colors. The are used to color RAW files, which only contain color indexes instead of real colors. ACT stands for Adobe Color Table.

Description

Each color contained has the length of 3 byte. Each byte represents one color component in the RGB color model. The position of the color in the file is its index (starting from 0).

The amount of colors numColors is the file size divided by 3.

Example: The MTM2 crazy98.pod contains the file ART\BACKHOE.ACT. The color at index 1 is 0x03 0x01 0x01 which in RGB is a slightly lighter black.

Structure

The ACT file structure is as follows:

color[0]
...
color[numColors - 1]

With decomposition:

color[i] = component[i][0], component[i][1], component[i][2]

With variables:

component[i][j]: color component in range [0...255]