The example above, identifies the following yarn:
E = electrical glass
C = continuous filament
G = average filament diameter of 0.00037″(9 Micron)
150 = 15,000 yards/lb. nominal bare glass in basic strand.
3/2 = two plies of 3-strand construction (total 6 basic strands)
3.0S = the number of turns per inch in the twist of the final yarn in the S direction