AST = Assistant Chief (OCFA has 8 of them! Basically 2 are operations orientated - Field Ops North and Field Ops South. Could also get the EMS Assistant Chief on an MCI/MVI of a large scale.
WS = Wildland Support Unit manned by Reserve FF's. Recently moved to FS 28 in Irvine from FS18 in Trabuco Canyon. Basically, a utility pickup with a small water tank and a pump, used for mop up. So small it doesn't fit into any ICS engine designations.
G = OCFA has 2 type 1 handcrews run out of FS 18 in Trabuco Canyon. G1 is the Santiago Handcrew and G2 is the El Toro Handcrew. The "G" designation comes from the ICS type letter that corresponds with type 1 crews. Like "A" would indicate a type 1 or structure engine and "C" would indicate a type 3 or wildland engine, "G" indicates a type 1 handcrew.
W = Don't have a clue, gonna have to dig in on that one.
Hope that helps,
Bill