X - X window system

X2B - Hexadecimal to Binary

X2C - Hexadecimal to Character

X2D - Hexadecimal to Decimal

XA - Extended Architecture

XAPIA - X.400 API Association

XBM - X - windows Bitmaps

XCMD - External Command

XCOPY - Extended Copy

XDF - Extended Density Format

XDM - X Display Manager

XDMCP - X Display Manager Control Protocol

XDR - External Data Representation

XFCN - External Function

XFCN - Extended Function

XFN - X / open Federated Naming

XGA - Extended Graphics Adapter

XGA - Extended Graphics Array

XID - Exchange Identifier

XIOS - Extended Input / Output System

XLL - Extensible Linking Language

XML - Excel Macro Language

XML - Extensible Markup Language

XMM - Extended Memory Manager

XMP - X / open Management Protocol