OVERVIEW
--------
Depending on the application, a programmer may want to allow only one
instance of his/her application to be executing at a time.  Typically,
this is needed to protect resources in some fashion.  You do NOT want
multiple instances to be able to modify the same file/database data,
create/manipulate/release/destroy system resources, or even occupy RAM
at the same time.  While most Windows-based programming languages do
provide some mechanism for determining if a previous instance is executing,
and some even provide handles to instances and previous instances, there
does not seem to be any "built-in" support for activating previous instance
windows.  When a user executes your program, you would like to be able to
switch-to/activate the window of a previous instance (if any) and exit,
to avoid running multiple application instances.  Not only does this allow
for protection of resources and conserves memory, but it also looks far
more professional to the user.  The Windows File Manager is a prime example
of this type of behavior.  Regardless of how many times you try to execute
the file manager, it always brings up the original instance.  This package
will allow you to do this previous instance window activation with your
application.  While there are a few packages that allow this, I have not
seen another one that is language independent.  Most, if not all, others
utilize task windows titles/caption text, class words, etc.  This package
does NOT use these techniques, and is entirely language independent.  Thus,
the DLL may be called/used by any application programming language that is
capable of understanding/using Windows DLLs.  This includes: Visual Basic,
Visual C++, Borland C++, Delphi, and others.  A Delphi DCU is also included
to provide this capability as a compiled unit which may be linked directly
into Delphi executables, as an alternative to using the DLL.


SYSTEM REQUIREMENTS
-------------------
The DLL and DCU files are 16-bit Windows 3.1x compatible code.  It is also
possible that the software may work with Windows 95, as W95 itself uses a
bit of 16-bit code.  The package has been completely tested under W3.1x,
Delphi 1.x, and Visual Basic 3.0, with no problem whatsoever.  If you test
the software under W95, remember that the only question is "does it work?",
as execution speed (16-bit vs. 32-bit) is not really an issue for this
type of software.  Before anyone asks, the software does NOT work with
Windows NT, as NT cannot use any 16-bit code.


VERSION
-------
This package constitutes the demo/evaluation version.  This demo version
works exactly like the registered version, with one exception.  The demo/
evaluation version is not intended for distribution with your applications,
and will sometimes display a demo/evaluation copy message when it is
executed.  The registered version does not display this message, and may
be distributed, royalty-free, with your applications which use the software.
Detailed order info is contained in the file ORDERFRM.TXT.  Registered
users will be issued a letter granting unlimited, royalty-free, non-exclusive
rights to distribute the software with calling applications.  Applications
which use this software may not contain any design information for this
software, or instructions on it's use in a design environment.  Unregistered
users may not distribute the registered version in any fashion, but this
demo/evaluation version may be freely distributed.  Distribution rights for
the registered version are valid for the registered user only, and may not
be transferred or conveyed to any other person or company for design or
distribution uses.  Before ordering, please take all the time that you need
for proper evaluation and testing of this product.  I would suggest testing
the product completely, to decide if it truly meets your needs.  Also,
please read all documentation, which should answer most questions.


PACKAGE CONTENTS
----------------
PREVINST.DLL - DLL callable from any Windows-based programming language.
PRVINST.DCU  - Delphi Compiled Unit, for linking directly into executables.
FILE_ID.DIZ  - Package description for software libraries and vendors.
README.TXT   - Overview, system requirements, general info, etc.
USAGE.TXT    - DLL and DCU declarations and usage instructions.
ORDERFRM.TXT - Order info/form for the registered/non-demo versions.


AUTHOR CONTACT INFO
-------------------
Before contacting the author with questions, please read all documentation
provided.  If you still have a question, feel free to contact the author.
Please limit questions to problems/usage items.  No questions will be
answered relating to the design techniques of this software itself.  That
being said, the author may be contacted (no phone calls, please) as follows:

        C. L. LANKFORD
        PREVINST
        108 MARSHALL ST. SW
        HARTSELLE, AL  35640-4106

        lankford@net-master.net
        http://www.net-master.net/~lankford/


DISCLAIMER
----------
THIS SOFTWARE AND THE ACCOMPANYING FILES ARE PROVIDED "AS IS" AND WITHOUT
WARRANTIES AS TO PERFORMANCE OR ANY OTHER WARRANTIES WHETHER EXPRESSED OR
IMPLIED.  BY USING THIS SOFTWARE, YOU EXPLICITLY ASSUME ALL RESPONSIBILITY
FOR ANY DAMAGES RESULTING FROM IT'S USE.  FURTHER, IF DISTRIBUTED WITH AN
APPLICATION, THE APPLICATION AUTHOR ASSUMES ALL RESPONSIBILITY TO THEIR
CLIENT FOR DAMAGES, WHETHER REAL OR IMAGINED.  UNDER NO CIRCUMSTANCES IS
THE AUTHOR OF THIS SOFTWARE RESPONSIBLE, LEGALLY OR OTHERWISE, FOR ANY
DAMAGES, WHETHER REAL OR IMAGINARY, RESULTING FROM IT'S USE.  ANY DESIGNER
OR PROGRAMMER NOT IN COMPLETE AGREEMENT WITH THIS DISCLAIMER SHOULD NOT
USE THIS SOFTWARE FOR ANY PURPOSES WHATSOEVER.