Not who they are but what it means. Clearly some kind of scale. A number for technological advancement and a letter for something else?
From Memory Alpha we have three scales:
A technological rating was a measurement of a planet's level of technology. http://www.memory-alpha.org/wiki/Technological_rating#See_also
The industrial scale was a system used to rate the extent of industrial development on different planets. http://www.memory-alpha.org/wiki/Industrial_scale#See_also
Richter's scale of cultures was a method of describing cultural achievement. http://www.memory-alpha.org/wiki/Richter's_scale_of_cultures#See_also
From Memory Alpha we have three scales:
A technological rating was a measurement of a planet's level of technology. http://www.memory-alpha.org/wiki/Technological_rating#See_also
The industrial scale was a system used to rate the extent of industrial development on different planets. http://www.memory-alpha.org/wiki/Industrial_scale#See_also
Richter's scale of cultures was a method of describing cultural achievement. http://www.memory-alpha.org/wiki/Richter's_scale_of_cultures#See_also