CAD tip # 8649:

You can also define and add your own custom color books containing your company colors (e.g. from your corporate identity kit), or colors of your product family (e.g. paints, enamels).

You can use two ways. The simpler one is to use the interactive "Autodesk Color Book Editor" - see Download. This utility will create the ACB file containing your RGB colors. This file can be then copied to the Support/Color folder to be automatically loaded into AutoCAD.

Another way is to manually define the XML file with the extension .ACB. This file has the following structure:

< ?xml version="1.0" encoding = "UTF-8"?>
< colorBook>
  < bookName>ACME Colors< /bookName>
  < colorPage>
    < pageColor>  < RGB8Encrypt> < redEncrypt>PPC< /redEncrypt> < greenEncrypt>QMH< /greenEncrypt> < blueEncrypt>QZB< /blueEncrypt> < /RGB8Encrypt> < /pageColor>
    < colorEntry>  < colorName>Color-1< /colorName> < RGB8Encrypt> < redEncrypt>LGH< /redEncrypt> < greenEncrypt>LHH < blueEncrypt>UZG< /blueEncrypt> < /RGB8Encrypt> < /colorEntry>
...

As you can see, the color hues are encrypted. But AutoCAD supports also (not documented) an unencrypted version of ACB files. These files differ only slightly from the above format:

< ?xml version="1.0" encoding = "UTF-8"?>
< colorBook>
  < bookName>ACME Colors< /bookName>
  < colorPage>
    < pageColor>  < RGB8> < red>100< /red> < green>100< /green> < blue>100< /blue> < /RGB8> < /pageColor>
    < colorEntry>  < colorName>Color-1< /colorName> < RGB8> < red>100< /red> < green>20 < blue>10< /blue> < /RGB8> < /colorEntry>
...

So you can type your color book manually in a XML editor or even in Notepad. You can also convert/generate such color book programmatically.