From LDraw.org Wiki

The !CMDLINE metacommand do have at present only one purpose: define the color that this part has under normal circumstances. Saying that all parts that have been produced only in one color should carry that metacommand. The syntax of this metacommand is simple. Example: !CMDLINE -c19 The '-c' is the parameter for colouring of the part and the number following (without whitespace) is the color number from LDConfig.ldr.

--Mikeheide 12:03, 23 June 2011 (EDT)