{HISTORY of BTP - the Btrieve Unit for Turbo Pascal 7.0       V2.0   6/10/93 }
(* ------------------------------------------------------------------------ *)

Version 1.0   4/9/91: Initial functioning unit, released 9/5/91.
--------------------

Version 1.1   9/8/91: Corrected a problem occuring in Btrieve files that had
--------------------  segmented keys with more than one segment.  The stats
   stored by the BFile.Init constructor were not calculating the number of
   segments properly.  The CreateFile function was also modified to deal with
   the same key problem.  This change forces one more statement to be placed
   in any 'create file' routine.  Any of the 24 key arrays not used in a file
   must have their key flags set to zero.  See Create.PAS for an example.

Version 1.2  9/16/91: NOT RELEASED PUBLICLY.
--------------------  Derived a new base object, BRecMgr, from what HAD been
   my base object, BFile.  It made sense to me to provide access directly
   thru an object to the basic, non-file, non-record oriented Btrieve
   operations: Begin/End/Abort Transaction, Version, Stop and Reset.  This
   BLOWS compatibility with any code you wrote under prior versions of this
   unit as the BT function is now virtual.  You should NOT call the ancestor
   BT function in your override...replace it completely as shown in the
   example programs and in BTP.DOC.

   BRecMgr has a variant record field to hold info on the version of Btrieve
   the user is running.  That data is set by BRecMgr.Init.

Version 1.3 10/11/91: Unit name changed to BTP.  Bug fixed that would give
--------------------  incorrect result in BFile.NumRecs if number of records
   exceeded 32,767.  Made a number of "touch-up" changes to make it easier to
   use dynamic variables of the various data types in BTP.  Note particularly
   that the CreateFile function now requires a second parameter, a pointer to
   a Btrieve file spec as defined in BTP.

   The constructors for BRecMgr and BFile now set up a string data field,
   VersionString, equal to the version number of Btrieve running in the user's
   computer.  This is in addition to establishing the record field Version,
   which contains the exact bytes returned by the Btrieve version call.

   All example programs were modified to reflect the changes in 1.2 and 1.3.

Version 1.4 10/27/91: Nomenclature of data types improved and made more
--------------------  consistent, both within BTP and with TP6's own internal
   Turbo Vision style.  TRecMgr and BFile are now separate "base" objects.
   Added BFixed and BFileExt objects, both descendants of BFile.  Together
   these permit handling any standard fixed-length file, and provide complete
   support for the get/step extended calls, including handling of all the
   drudgery of constructing data buffers.  This was no small task!  For
   extended calls, you need simply insert your filter and extractor specs into
   the provided collections in BFileExt.  The rest of the setup is transparent
   to you, being handled by the object's internal methods and your standard
   override of the BTExt function.

   An object of type BFileExt can freely entertain both standard BT and
   extended BTExt calls thanks to encapsulation of the position block in the
   object (see EXAMPLE2.PAS).  However, I recommend use of BFileExt only if
   you are truly going to use extended calls for a particular file.  This is
   because there is about 32K more overhead per BFileExt object than BFile.
   The size of a BFile object is 698 bytes.  The size of a BFileExt object is
   722 bytes, plus the size of the extended data buffer, which I default to
   32767 bytes, plus the size of any items inserted into the two collections.
   Note that the size of a BFixed object is 5043 bytes, to hold room for a
   buffer equal to the maximum size of a fixed length record, and the maximum
   length of a key.

   BFile and its descendants now take an Open mode parameter.

   The BFile.BT virtual function is now Abstract, to assure you don't call
   it without overriding it.

   The BFileExt.BTExt method must be overridden, with the override calling
   the ancestor; i.e. your override must be of a standard form, and must call
   BFileExt.BTExt.  This is because BFileExt.BTExt is what sets the buffer
   length and constructs the buffer for extended read calls.  This is in
   contrast to BFile.BT or BFileExt.BT, which must be overridden by REPLACING
   them, as shown in the example programs and in BTP.DOC.

   BFileExt's data fields include two collections.  The FilterSpec collection
   need not hold any objects, but the ExtractorSpec must always hold at least
   one.  Now, for extended calls, you handle these data fields as follows
   (see EXAMPLE2.PAS):
   1:  HEADER is handled internally.  Don't mess with it.
   2:  FILTER's fields are assigned by your program.
   3:  FILTERSPEC collection may or may not hold any objects, depending on
       your program's needs.
   4:  EXTRACTOR must be initialized.
   5:  EXTRACTORSPEC collection must hold at least one object.
   6:  EXTDBUFFER is handled internally.  Don't mess with it, except to
       use it as shown in EXAMPLE2.PAS when you override BFileExt.BTExt.


   BTP 1.4 IS THE FIRST *SHAREWARE* RELEASE.  The BTP product is no longer
   FreeWare.

Version 1.5 11/9/91: New in this release...complete support for alternate
-------------------  collating sequences.  This required modifying the BFile
object and its constructor, and the CreateFile function, and the addition of
data structures for an alternate collating sequence file.  A boolean field in
BFile, HasAltCol, has been established.  The CreateFile function now takes a
third parameter, being the name of an alternate collating sequence file, if
any.
   Also changed in this version:
   BFile has an additional field for a file's actual filespec length.  This
can be useful when cloning a file.  A new function, CloneFile, has been
added, which reduces the cloning process to a single function call, with only
the names of the existing and new files passed as parameters.  Miscellaneous
changes in V1.5 include elimination of a redundant parameter previously
required by the FilterSpec object's constructors.  Added a variant to both
the FileSpec and KeySpec objects to allow easier reporting of certain stats
after a stat call.
   Some minor optimizations done here and there thruout the unit and example
programs.
   BEST NEWS!  The STATS program has been greatly enhanced.  It now produces
substantially the same output as 'BUTIL -STAT', but is a standalone program
and can be freely distributed with your applications (unlike BUTIL) IF YOU ARE
A REGISTERED USER of BTP.

Version 1.6 11/25/91: Corrected a typo in example CREATE1.PAS.  Changed the
--------------------  CloneFile function significantly.  It can now clone a
file with supplemental indexes...and do one of the following with such
indexes: drop them (keeping only the permanent indexes), retain them as
supplemental indexes, or make all supplemental indexes permanent.  The
STATS program was updated only to add the ability to report on/identify
supplemental indexes.  To the best of my knowledge, the STATS program can
now truly be said to be a COMPLETE replacement for any information reported
by BUTIL -STAT.

Version 1.7 1/11/92: RELEASED ONLY TO REGISTERED USERS.  Corrected a potential
-------------------  problem in the BFile.Init method and CloneFile functions.
Use of typed constants versus variables would create problems due to those
data items retaining values between calls.  Replaced them w/variables.  Bug
only seemed to appear if a TP6 unit was created using BTP.TPU, and that unit
was then used in a separate source program.

Version 1.7A 2/28/92: Corrected a minor bug that could appear with Btrieve
--------------------  files of a full 24 key segments.  The CountSegments
procedure in both BFILE.INIT and CREATEFILE() had an incorrect expression
as a termination test in a REPEAT..UNTIL loop.

Version 2.0  6/10/93:  Numerous changes throughout the product.
--------------------
NOTE: This version breaks compatibility with prior releases in a number of
      places.  Most constructors take additional parameters (owner name the
      most significant).
1.  Rewritten to make use of several features of TP/BP 7.0, such as the
    "inherited" and "const" keywords, and the use of open arrays in at least
    one place.
2.  Enhancements throughout the product to handle owner names.  The base
    object BFile, and the CreateFile and CloneFile functions were enhanced
    to readily deal with owner names.
3.  Added a descendant of BFile, BSized.
4.  Added the AddSuppIdx function to the base object, BFile.  This makes it
    trivial to add a supplemental index to a file.  Uses its own internal
    buffers, not disturbing your "working" buffers.
5.  Major improvements to the CreateFile function (see CREATE1.PAS and
    CREATE2.PAS) that permit Btrieve file creation with two program
    statements.  This was made possible in part by the new function
    NewKeySpec.
6.  Some nomenclature changes made for consistency.
7.  Minor other cosmetic changes to code in the BTP unit.  No known bugs, per
    se, were found or corrected.
8.  The example and utility programs were rewritten, and in some cases over-
    hauled.  The STATS, CLONE and CRUNCHx programs now deal with owner names.
    The EXAMPLEx programs are hopefully more meaningful and helpful.

