DoubleSpace API Error/Return Codes

 The DoubleSpace API (INT 2fH 4a11H and related IOCTL fns) may return the
 following error codes:

INT 2fH Error Codes

 0000H I2F_NO_ERR              fn was successful
 0100H I2F_ERR_BAD_FN          invalid fn number in BX
 0101H I2F_ERR_BAD_DRV         invalid drive number specified
 0102H I2F_ERR_NOT_COMPR       specified drive number is not compressed
 0103H I2F_ERR_ALREADY_SWAPPED host drive already swapped
 0104H I2F_ERR_NOT_SWAPPED     drive is not swapped (I assume that this is
                               returned by an undocumented fn)

IOCTL and INT 2fH 4a11H 0005H (mount volume) Error Codes

 4f4bH OK_NO_ERROR             The IOCTL calls return 'OK' in the bResult
                               field of the IOCTL packet if no error.

   01H LETTER_BOUNDARY_ERROR   Drive letter not available for DoubleSpace
                               (use a drive letter between FirstDrive and
                               LastDrive; see INT 2fH 4a11H 0000H)
   02H UNIT_USED_ERROR         Drive letter already in use (use an unused
                               drive letter)
   03H NO_FREE_SLOT_ERROR      No more disk units (increase the
                               MaxRemovableDrives setting in DBLSPACE.INI)

   09H TOO_CLUTTERED_ERROR     CVF is too fragmented (increase the
                               MaxFileFragments setting in DBLSPACE.INI)
See Also: DoubleSpace Overview
          DoubleSpace API
          INT 2fH: Multiplex Interrupt
          DOS Functions