XDM/X Model  Experimental Development Model/Exploratory Development Model
Xfer  Transfer
XIDB  Extended Integrated Database
XMIT  Transmit
XMTR  Transmitter
XO  Executive Officer
XOI  USAFE Director of Intelligence
XOIN  USAFE Combat Operations Division
XOIX  USAFE Plans & Systems Division
XP  Director(ate) of Plans
XRL  X-Ray Laser
XTR  Transmitter
XVIII ABC  XVIII Airborne Corps