The DoubleSpace support driver (DBLSPACE.BIN) reads the text file,
  DBLSPACE.INI, in order to decide which CVFs to access and what drive
  IDs to use.  This topic describes the contents of DBLSPACE.INI.

  DBLSPACE.INI is in the root of the physical boot disk (it is typically
  swapped to an ID such as H: or I: by the time you look for it).  It has
  read-only, hidden, and system file attributes; use Dir /A to see it

  You can edit the file with any text editor, such as the DOS Edit command.
  You must clear its attributes first (Attrib H:\Dblspace.ini -H -S -R).

  Before making changes, I recommend that you prepare a boot diskette with
  an editor and other tools.  Oh, yeah -- make a copy of DBLSPACE.INI, too.

█▌DBLSPACE.INI Commands▐█

   DoubleSpace maintains a series of structures to keep track of mounted
   drives.  At boot time, DoubleSpace allocates memory for one structure
   for each drive which was activated plus an extra n such structures.
   See INT 2fH 4a11H 0009H (Count DISK_UNIT structures).

   A normal setting: MaxRemovableDrives=2

   To change: Choose Options in the Tools menu.

   Specifies the lowest drive letter available for a host or compressed
   drive.  DoubleSpace ignores FirstDrive and simply takes control of
   all drive IDs starting from the original ID of the disk that contains
   the first CVF mounted (see ActivateDrive, below).

   Specifies the highest drive letter available for a host or compressed

   Notes: ■ DoubleSpace assigns drive IDs starting at LastDrive and working
            down toward FirstDrive.

            DoubleSpace will increase LastDrive automatically when
            necessary.  For instance, if you mount a volume from a high-
            lettered drive, DoubleSpace will need to consume drive letters
            up to and including that drive's original ID.

          ■ See INT 2fH 4a11H 0001H (get drive map).

   When a CVF is fragmented, DoubleSpace must maintain an internal
   structure to keep track of each fragment (this avoids having to hit
   the FAT of the host).  This command determines how much memory to
   allocate.  See INT 2fH 4a11H 0008H (get CVF Fragmentation Info).

   During installation, nnnn is set to a whopping 2600.  That's because
   a CVF may need to be created in multiple, discontiguous sections when
   the host disk is large and has little free space.

   But 2600 is a worst-case scenario.  After the initial installation,
   MaxFileFragments is adjusted automatically to reflect the actual
   memory needs.  It is set to the actual number of file fragments on
   all CVFs plus a fudge factor of 110.

   To see how fragmented your CVFs ended up, subtract 110 from the
   current setting.

                │ │└────── CVF number (0-9)
         drv1 ──┘ └─────── drv2

   One or more of these ActivateDrive= commands appear at the end of
   DBLSPACE.INI.  Each command identifies the locations of a hard disk
   volume to mount automatically at system startup, and the drive ID to
   use for it and its host.

   n specifies which CVF to mount.  It is a digit, 0 to 9--the last
   digit of the CVF file extension.

     See INT 2fH 4a11H 0005H (mount volume) and
     See INT 2fH 4a11H 0002H (swap drive IDs)

  If n is 0
    The volume was created by compressing existing files.  The compressed
    volume ID will be swapped with the host ID, so...

    drv1 is the drive letter to be used for the host.
    drv2 is the drive letter to be used for the compressed volume.  It also
    identifies the original (unswapped) ID of the drive on which the CVF is

    Example: ActivateDrive=H,C0
    The file C:\DBLSPACE.000 is mounted and IDs are swapped.  The host ID
    will be H: and the compressed volume will be called C:.

  If n is not 0
    The volume was created by compressing free space.  The compressed
    volume ID will not be swapped, so...

    drv1 is the drive letter to be used for the compressed volume.
    drv2 is the original drive letter of the host.

  Example: ActivateDrive=G,C1
     Mounts C:\DBLSPACE.001 as drive G:.  No swapping occurs.

  Example: ActivateDrive=H,C0
    C:\DBLSPACE.000 is mounted as drive C: and the host ID is swapped and
    can be accessed as drive H:.

    C:\DBLSPACE.001 is mounted for access as drive D:.  The host ID was
    swapped in the first line, so DBLSPACE.001 will be on drive H.

    Note: When changing these settings, be sure to assign drive letters
          that are within the range of FirstDrive= and LastDrive=.

   These two commands are recognized by Dblspace.Exe, but are
   undocumented in any source I could find.  I would guess, that
   Enable386= lets DoubleSpace support use 32-bit optimized compression
   code and would only be needed on a machine that appears to be a 286
   but is really a 386+.  The Debug= line may be an undeleted remnant
   from beta tests; DBLSPACE.BIN does not recognize it.

See Also: DoubleSpace (overview)