Within your TM1 data directory you may find some files with the extension .blb
These files actually store the formatting of your .rux files.
e.g.
If you maintain your rules in backend TM1 (rather than Excel worksheets) then you may have GL.cub and a GL.rux
If you format the text in the .rux to be font size 12 and blue than a GL.blb will appear storing that formatting. Sometimes you may create one without realising it though.
I actually find blb files to be a bit annoying and I have had issues with them, so I tend to delete when I see them.
Personally I think rules are easier to maintain in Excel worksheets but I occasionally use backend rule files on my control cube rules.
