X;
X-1;
X11R4;
X11R5;
X11R6;
X.12;
X2;
X.208;
X.209;
X.21;
X.214;
X.215;
X.216;
X.217;
X.219;
X.224;
X.225;
X.226;
X.227;
X.229;
X.25;
X.28;
X.29;
X.3;
X3J16;
X3T10;
X.400;
X.409;
X.500;
X.680;
X.75;
x86;
x86 processor socket;
XA;
Xaw;
Xbase;
xbeeb;
xbm;
XC;
X client;
X Consortium;
Xcoral;
xdbx;
X-Designer;
X.desktop;
XDL;
XDR;
XDS 530;
XDS 940;
xDSL;
Xemacs;
XENIX;
Xeon;
XEROX Corporation;
Xerox Data Systems Model 530;
Xerox Data Systems Model 940;
XEROX Network Services;
Xerox Network System;
XEROX PARC;
Xerox Star;
XFree86 Project, Inc.;
Xfun;
XGA;
XGA-2;
XHTML;
Xi;
XIE;
Xilinx, Inc.;
Xilinx Netlist Format;
X Image Extension;
Xlib;
xlisp;
xls;
XML;
XML schema;
XML Template Pages;
XML User-Interface Language;
XMM;
XMODEM;
XMODEM-1K;
xmosaic;
XMS;
XNF;
xnf2ver;
XNS;
XOFF;
XON;
XON/XOFF;
Xopen;
X/Open;
X/open Portability Guide;
X/Open System Interface;
xor;
XPC;
XperCASE;
XPG;
XPG3;
XPL;
xpm;
XPOP;
Xpress Transport Protocol;
X protocol;
xref;
XRemote;
XRN;
XSB;
XScheme;
x-scm;
XSD;
X server;
XSI;
XSL;
XSLT;
XT;
Xt;
XT bus architecture;
xterm;
X terminal;
XTI;
XTP;
XTP Forum;
XTRAN;
XUI;
XUL;
Xv++;
XVGA;
XView;
XVT;
X-Windows;
X Window System;
XWIP;
xxgdb;
XXX;
Xy-pic;
xyzzy;