DOS related functions:
  Overview        About these routines
  XPdosMajor()    Returns the DOS Major version number
  XPdosMinor()    Returns the DOS Minor version number
  XPdosVersion()  returns the current DOS version as a string
  XPdosValue()    returns the current DOS version as a number
  XPappendThere() Report whether APPEND is installed.
  XPappendPath()  Return APPEND's PATH.
  XPkeybCode()    Return Country Code as set by KEYB.COM
  XPkeybUSA()     Set KEYBoard to standard mode (US).
  XPkeybNorm()    Set KEYBoard to normal (selected) mode.
  XPmyName()      Return program's own name
  XPcommandLine() Returns the Full Command Line parameters
  XPdosMsg()      Return information about a DOS error code                  .