This system variable is a two dimensional table that you can edit to control syntax coloring in expression fields such as definitions in object windows and in the attribute pane. This is indexed by Sys TokenType and Sys RedGreenBlue. The table is stored in the registry and read from there at startup. Any editing changes you make will update the registry, if these changes are valid.
Here is the table with initial values:
red green blue
comments 0 255 0 text literals 255 0 0 keywords 0 0 255 variables 191 0 191 identifiers 127 0 127
The row and column headers are not editable, and you cannot add any rows or columns. Only the data cells can be changed, and these cells only allow integer values between 0 and 255, inclusive. Any other values will cause an error and you will get an error popup explaining these rules and suggesting that you correct your error. If you say yes, go back to editing, the edit table will revert back to was it was before.
The rows give the RGB components of the colors used in expression fields for various syntactic categories.