The typical description I put for any given style of fiberglass cloth will go something like 4 oz/sq yd, 30x30 ends/inch thread count, uses the yarn ECG75 1/0 in the warp and fill. The oz/sq yd is for the actual ounces per square yard of the fabric. (This is the only time I ever use square yards is in the identification of the cloth. All cloth sold by Thayercraft is by the linear yard.) The next component of the fabric description is the thread count and is the number of warp yarn per inch first and then the number of fill yarn per inch. The same as you would lay a ruler down and count the warp threads (the ones that go long ways down the cloth) and the number of fill thread - side to side yarn - per inch. The next component is the description of the yarn being used. In my example I put the same for both warp and fill which is ECG75 1/0. The "E" means it's the common electrical type (could also be C or S), the second letter "C" just means its continuous monofilament rods. The third letter "G" is the filament size designator which for G is 9 microns. The "75" part of ECG75 defines how many yards per pound the yarn is and you always add two zeros to this number. For ECG75 there are 7500 yards per pound of this yarn. The 1/0 means there are only one G75 yarn being used. If it was ECG 75 1/2 it would be two G75 yarn together. Some other abbreviations used are: 4HS: Four Harness Satin, 8HS: 8 Harness Satin, PW: Plain Weave. The phrase "in the greige" is used a lot and has nothing to do with a color. Greige means the cloth is in the loom state and still has the PVA on it - good for silicone rubber coating but not good for resins. Unidirectional means the yarn, generally the warp yarn, is of greater number and weight than the other yarn.