I'd like to create a few custom in-game artwork files (bezels in particular) for various games running on an older version of MAME. However, I can't find anything that explains how to set up the .art file. I understand all the options except for the "position" option. I know it's left,top,right,bottom - but is that in pixels or what as I see some other files have negative values, so I'm a little confused on how to figure out what to use for these values.
As an example: