FT_ISSHARE()
 Determine if DOS "Share" is installed
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 Syntax

       FT_ISSHARE() -> nRetCode

 Arguments

      None

 Returns

      nRetcode will be set as follows on exit:

          0 if SHARE not loaded but ok to load
          1 if SHARE not loaded and not ok to load
        255 if SHARE loaded

 Description

      Uses DOS interrupt 2Fh (MultiPlex interrupt), service 10h
      to determine if DOS SHARE.COM is loaded.

 Examples

     IF FT_ISSHARE() != 255
        Qout("SHARE must be loaded!")
     ENDIF

 Source: ISSHARE.PRG

 Author: Glenn Scott (from Tom Leylan C source)