The methods relating to sorting in the auction house can operate on many columns, this identifier is used to indicate which column is being referenced. Valid values are:
Values[]
"quality"- Item quality (All types)
"level"- Item level (Only "list", "bidder")
"duration"- Auction duration (All types)
"buyout"- Current buyout price? (Only "bidder")
"status"- Status (High bidder or not??) (All types)
"bid"- Current bid (All types)
Notes[]
Not all of these sorts are valid for all auction types, those which are seen in the WoW UI code are indicated.