A similar notation for fractional units is used to write formulas for tinting paint. Sometimes you'll see paint color formulas written as a matrix of fractional

A similar notation for fractional units is used to write formulas for tinting paint. Sometimes you'll see paint color formulas written as a matrix of fractional fluid ounces for each colorant, but they skip some fractions so that the positional values are sometimes 2 or 3. I suppose this makes it a base 4 representation.