Usual Gauges

AWG American Wire Gauge Similar to Brown and Sharp. Gauges used mainly for non-ferrous sheet, rod, wire and tubing
B&S Brown & Sharp Similar to AWG
BWG Birmingham Wire Gauge Similar to Stubs' Iron Wire Gauge (1). These gauges are mainly used for strips, bonds, hoops, wire and tubing.
BG Birmingham Gauge 1884  
SWG Standard Wire Gauge (British) Similar to British Imperial Standard Gauges, mainly used for English legal standard wire gauges and tubing.
USG United States Standard Gauge (old) or U.S. Government Standard Mainly used for stainless steel sheets
US U.S. Steel Wire Gauge or Steel Wire or American Steel and Wire or Washburn & Moen's Gauge Mainly used for steel wire, except for music wires
MSG Manufacturers' Standard Gauge Mainly used for uncoated steel sheets
GSG Galvanized Iron  
AZG American Zinc Gauge  
OTHERS Paris Gauge / Westphalia Gauge  

(1) Is not Stubs' Steel Wire Gauge