Q=bogus "fuel surcharge"
US=U.S. Air Transportation Tax (7.5%)
XF=U.S. Passenger Facility Charge (up to $18)
XT=Combined taxes (the "too many taxes" tax)
XY=U.S. Immigration and Naturalization User Fee ($6, for travel into U.S.)
ZP=Flight Segment taxes ($2.75/segment)