FT_EXIST()
 Test for drive and/or subdir on SINGLE-USER systems only.

 Syntax

      FT_EXIST( <cDriveDir> ) -> lResult

 Arguments

     <cDriveDir> is a character string containing drive spec (with colon)
     or drive spec and path to and including subdirectory being tested
     for.  Do not include backslash after subdirectory.  If drive spec
     is not part of string, the current drive is tested.

 Returns

     <lResult>  as logical -
     .T. if drive exists, or subdirectory exists on specified drive
     .F. if drive or subdirectory does not exist

 Description

     FT_Exist() tests for the existence of a drive and/or subdirectory...
     on single-user systems ONLY.  You may get correct results on some
     networks under certain conditions, but this function is not capable
     of working reliably on networks.

 Examples

    IF FT_EXIST( "D:" )
       Qout("OK To Perform Operation On Drive D:")
    ENDIF

 Source: EXIST.PRG