XA
XB
X-BAND X-CHANNEL
XBLEED
X-Channel
XCHECK
XCVR
XDCR
XFEED
XFER
XFILL
XFMR
XFR
XID
XIFD
XLS
XLTR
XM
XMIT
XML
XMTR
XMTR/RCVR
XP1
XP2
XP3
XP4
XP5
XPD
XPDR
XPTR
X-RAY
XRT
XS
XSIDE
XTI
XTK
XTK DEVIATION
XTP
XWIND