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Subject: CLIPS Frequently Asked Questions
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                    CLIPS FREQUENTLY ASKED QUESTIONS
                           November 30th, 1993            
                    
This is the frequently asked questions list for CLIPS. A current
version of this file, clips-faq, is available by anonymous ftp from 
hubble.jsc.nasa.gov in the directory /pub/clips. Comments/Suggestions
about this list can be sent to Gary Riley. My email address is 
riley@gothamcity.jsc.nasa.gov. If you have a special version of CLIPS, 
CLIPS programs, or anything else that you'd like to make available to 
other CLIPS users, send email as well.

CONTENTS
--------
 1) What is CLIPS?
 2) Where can I get a copy of CLIPS?
 3) What's new in version 6.0 of CLIPS?
 4) Can CLIPS be redistributed? Are there any licensing fees?
 5) What forums are available for answering questions about CLIPS?
 6) Are there any bug fixes for CLIPS?
 7) Is there an Ada version of CLIPS?
 8) When's the next CLIPS conference?
 9) Is the CLIPS User's Group still active?
10) Are there any copies of the CLIPS Conference Proceedings left?
11) Are there any recent reviews of CLIPS?
12) Are there any sources describing applications built using CLIPS? 
13) Are there any textbooks using CLIPS?
14) Are there any special versions of CLIPS?
15) Can CLIPS access extended memory beyond the DOS 640K limit on a PC?
16) Can CLIPS be compiled using a C++ compiler?
17) Does COOL store its objects as C++ data structures? 
    Are there any plans to convert CLIPS to C++?
18) How can I integrate CLIPS as a C program with other C++ programs?
19) Is a Dynamic Link Library Available for the Windows version of CLIPS?
    How do I use CLIPS with other Windows 3.1 applications?
20) What are the origins of CLIPS?
21) Are there any languages similar to CLIPS?
22) Did Inference aid in the development of CLIPS?
23) What are the future plans for CLIPS?


 1) WHAT IS CLIPS?
------------------
    CLIPS is a productive development and delivery expert system tool which
    provides a complete environment for the construction of rule and/or 
    object based expert systems. CLIPS is being used by over 5,000 users 
    throughout the public and private community including: all NASA sites 
    and branches of the military, numerous federal bureaus, government 
    contractors, universities, and many companies. The key features of 
    CLIPS are: 

    *  Knowledge Representation: CLIPS provides a cohesive tool for handling 
       a wide variety of knowledge with support for three different 
       programming paradigms: rule-based, object-oriented and procedural. 
       Rule-based programming allows knowledge to be represented as 
       heuristics, or "rules of thumb," which specify a set of actions to be 
       performed for a given situation. Object-oriented programming allows 
       complex systems to be modeled as modular components (which can be 
       easily reused to model other systems or to create new components). 
       The procedural programming capabilities provided by CLIPS are similar 
       to capabilities found in languages such as C, Pascal, Ada, and LISP.
    
    *  Portability: CLIPS is written in C for portability and speed and has
       been installed on many different computers without code changes. 
       Computers on which CLIPS has been tested include IBM PC compatibles,
       Macintosh, VAX 11/780, and Sun 3/260. CLIPS can be ported to any 
       system which has an ANSI compliant C compiler. CLIPS comes with all 
       source code which can be modified or tailored to meet a user's 
       specific needs.
    
    *  Integration/Extensibility: CLIPS can be embedded within procedural 
       code, called as a subroutine, and integrated with languages such as 
       C, FORTRAN and ADA. CLIPS can be easily extended by a user through 
       the use of several well-defined protocols.
    
    *  Interactive Development: The standard version of CLIPS provides an
       interactive, text oriented development environment, including 
       debugging aids, on-line help, and an integrated editor. Interfaces 
       providing features such as pulldown menus, integrated editors, and
       multiple windows have been developed for the Macintosh, Windows 3.1, 
       and X Window environments.
    
    *  Verification/Validation: CLIPS includes a number of features to 
       support the verification and validation of expert systems including 
       support for modular design and partitioning of a knowledge base, 
       static and dynamic constraint checking of slot values and function 
       arguments, and semantic analysis of rule patterns to determine if 
       inconsistencies could prevent a rule from firing or generate an error.
    
    *  Fully Documented: CLIPS comes with extensive documentation including 
       a Reference Manual and a User's Guide.

 2) WHERE CAN I GET A COPY OF CLIPS?
------------------------------------
    CLIPS version 6.0 is available at no cost to U.S government agencies
    and their contractors for use on U.S. government projects from the 
    Software Technology Branch Help Desk. For more information, contact
    
       Software Technology Branch Help
       Telephone (713) 286-8919
       Fax (713) 286-4479
       EMail stbprod@fdr.jsc.nasa.gov

    To order from the STB Help Desk, U.S. government employees must submit
    a request in writing on agency stationary. The request should include
    their name, organization name, organization address, and phone number.
    Contractors must also include their U.S. government contract number and 
    the name and phone number of their government contracting officer. 
    Software can not be sent to home addresses. Along with the letter
    include the appropriate media for storing the software: either two
    Macintosh high density 3 1/2" disks, two PC high density 3 1/2" or
    5 1/4" disks, four PC low density 5 1/4" disks, or one Sun DC600 data
    cartridge. Send the letter and disks to
    
       Lincom Corporation
       1020 Bay Area Blvd.
       Suite 200
       Houston TX, 77058
    
    CLIPS version 6.0 is available from COSMIC. For new orders, the cost is 
    $350 for the program and $115 for printed documentation. For update 
    orders, the cost is $100 for the program or $200 for the program and 
    printed documentation. Price discounts are available to U.S. academic 
    institutions. For more information, contact
    
       COSMIC
       382 E. Broad St.
       Athens, GA  30602
       Telephone (706) 542-3265
       Fax (706) 542-4807 
       EMail service@cossack.cosmic.uga.edu
    
    CLIPS version 6.0 is available on an ISO-9660 format CD-ROM from the 
    Network Cybernetics Corporation. Over 3,000 AI related files are 
    included on the CD-ROM. The cost is $129 + $5(domestic)/$10(foreign) 
    shipping. For more information, contact
      
       Network Cybernetics Corporation
       Wingren Rd., Suite 202 
       Irving, TX 75062-2763
       Telephone (214) 650-2002
       Fax (214) 650-1929
   
    CLIPS version 6.0 is available from the Austin Code Works for $50.
    For more information, contact
    
       The Austin Code Works
       11100 Leafwood Lane
       Austin, Texas 78750-3409
       Telephone (512) 258-0785
       Fax (512) 258-8831
       BBS (512) 258-8831
       EMail acw!info@uunet.uu.net

    CLIPS is available via anonymous ftp from ftp.ensmp.fr (192.54.148.100).
    The directory /pub/clips/clips-5.0, contains compressed files for the 
    Macintosh version of CLIPS 5.0. The directory /pub/clips/clips-5.1 
    contains compressed files for the MS-DOS version of CLIPS 5.1. The 
    directory /pub/clips/incoming contains the CLIPS 5.1 documentation in 
    both postscript and Word for Windows format. Files for creating a 
    CLIPS 5.1 dynamic link library for Windows are also available.

 3) WHAT'S NEW IN VERSION 6.0 OF CLIPS?
---------------------------------------
    CLIPS version 6.0 contains the following major enhancements and changes:

    *  Instances of user-defined clases in COOL can be pattern-matched
       on the left-hand side of rules.

    *  The defmodule construct allows a knowledge base to be modularized
       and partitioned.

    *  Not conditional elements may now contain CEs other than pattern CEs.
       The exists and forall CEs have been added. Connective constraints
       can be used with multifield variables.

    *  Static and dynamic constraint checking are supported to a much greater
       extent than in CLIPS 5.1. In addition to deftemplates, COOL also 
       performs constraint checking. Many of the features previously available 
       in CRSV are now directly supported in CLIPS.

    *  Deftemplates can now contain more than one multifield slot.

    *  The syntax for the defclass construct has been considerably
       changed.

    *  A Windows 3.1 CLIPS interface is now available for PC compatible
       computers. In addition, an MS-DOS 386 version of CLIPS is available
       which can use extended memory.

 4) CAN CLIPS BE REDISTRIBUTED? ARE THERE ANY LICENSING FEES?
-------------------------------------------------------------
    Copies of CLIPS purchased through COSMIC can be freely used and
    redistributed without restrictions. This is the mechanism through 
    which companies, such as the Austin Code Works or Network Cybernetics 
    Corporation, can redistribute CLIPS. The redistribution restrictions, 
    or lack thereof, also apply to any individual or company that has a
    copy of CLIPS that can trace its origins back to a purchase from 
    COSMIC. For example, if you buy a copy of CLIPS from the Austin Code 
    Works or you download a copy of CLIPS from an anonymous ftp site that 
    purchased a copy from COSMIC, you can freely use and redistribute the 
    copy you obtained.
    
    Users who receive CLIPS from the Software Technology Help Desk may
    only use CLIPS in connection with the specific project under which it 
    was provided and no further use or dissemination can be made without 
    prior written permission.

 5) WHAT FORUMS ARE AVAILABLE FOR ANSWERING QUESTIONS ABOUT CLIPS?
------------------------------------------------------------------
    If you have problems using or installing CLIPS, the Software Technology 
    Branch (STB) Help Desk can be contacted at (713) 286-8919 from 9:00 a.m. 
    to 4:00 p.m. (Central Standard Time). Leave your name and number and a 
    support person will get back to you. The STB Help Desk can also be 
    reached via electronic mail at <stbprod@fdr.jsc.nasa.gov> or by FAX at 
    (713) 286-4479. 

    An electronic conferencing facility is also available to CLIPS users. 
    Subscribers to this facility may send questions, observations, answers, 
    editorials, etc., in the form of electronic mail to the conference. 
    All subscribers will have a copy of these messages reflected back to 
    them at their respective electronic mail addresses to process at their 
    leisure. All that is required is that you have an electronic mail address 
    that is accessible either directly on the Internet or via a gateway 
    connected thereto (e.g., BITNET or NASAMAIL). To subscribe, simply send 
    a single line message to listserv@cossack.cosmic.uga.edu saying 
    SUBSCRIBE CLIPS-LIST (the hyphen is required).  The subject field is 
    ignored but the address found in the 'Reply:', 'Reply to:', or 'From:' 
    field will be entered in the distribution list.  Upon subscription you 
    will receive a mail message instructing you how to participate in the 
    conference from that point forward.

    Usenet users can also find information and post questions about CLIPS 
    to the comp.ai.shells news group.
    
    An anonymous ftp site maintained by the CLIPS development team can be
    accessed at hubble.jsc.nasa.gov. Bug fixes and other CLIPS related
    information is contained in the /pub/clips directory. The file read-me
    describes the contents of the clips directory.
    
    The STB Bulletin Board is no longer available.
    
 6) ARE THERE ANY BUG FIXES FOR CLIPS?
--------------------------------------
    A list of bug fixes for CLIPS 6.0 and the replacement source  
    files to fix the bugs are available by anonymous ftp from 
    hubble.jsc.nasa.gov in the directory /pub/clips/Bug-Fixes. 
    
 7) IS THERE AN ADA VERSION OF CLIPS?
-------------------------------------    
    CLIPS/Ada version 4.4 is a version of CLIPS developed entirely in Ada 
    and containing a subset of the features found in the C version of CLIPS.
    CLIPS/Ada version 4.4 contains all of the features found in CLIPS/C
    version 4.3, and with the exception of the CLIPS Object-Oriented 
    Language, all of the features found in CLIPS/C version 5.0. There are
    currently no plans to update CLIPS/Ada to a more recent version of
    CLIPS/C. CLIPS/Ada can be obtained through the Software Technology 
    Branch Help Desk (free for NASA and its contractors) or COSMIC
    ($400 for the program and $21 for the documentation). 

 8) WHEN'S THE NEXT CLIPS CONFERENCE?
---------------------------------------------
    The next CLIPS conference is scheduled for October 1-3, 1994 
    at the Johnson Space Center. The conference will also feature 
    other products developed by the Software Technology Branch  
    including NETS, COSTMODL, Splicer, and TARGET. More information  
    will be forthcoming in a few weeks.
    
 9) IS THE CLIPS USER'S GROUP STILL ACTIVE?
-------------------------------------------
    Apparently not. Several individuals have had problems contacting
    all but a few of the officers. At the next CLIPS conference,
    we'll try to determine if there's enough interest to warrant
    restarting the group.

10) ARE THERE ANY COPIES OF THE CLIPS CONFERENCE PROCEEDINGS LEFT?
------------------------------------------------------------------
    At last count, the STB Help Desk had about a half dozen copies
    of each the first and second conference proceedings left over
    (see question #2 for information on contacting the STB Help Desk
    to obtain a copy).

11) ARE THERE ANY RECENT REVIEWS OF CLIPS?
------------------------------------------
    The two most recent reviews of CLIPS are "The Art of Production
    Systems" by Tom Brooke in the January 1992 issue of AI Expert
    and "A Comparative Evaluation of Expert System Tools" by
    William Mettrey in the February 1991 issue of IEEE Computer.
        
12) ARE THERE ANY SOURCES DESCRIBING APPLICATIONS BUILT USING CLIPS? 
--------------------------------------------------------------------
    There are a number of source describing applications built 
    using CLIPS. The 1st and 2nd CLIPS Conference Proceedings are
    a good place to start. In addition, the STB Help Desk has a 
    booklet containing CLIPS application abstracts (see question #2 
    for information on contacting the STB Help Desk to obtain a copy).
    The abstracts booklet is also available via anonymous ftp from
    hubble.jsc.nasa.gov. The /pub/clips/Documents directory contains 
    a binhexed self extracting archive of the abstracts booklet in 
    Macintosh Microsoft Word format.
    
    The Proceedings of the First, Fourth, and Fifth Innovative 
    Applications of Artificial Intelligence also contain descriptions
    of applications built using CLIPS ("An Intelligent Training System 
    for Space Shuttle Flight Controllers" and "Space Shuttle Telemetry 
    Monitoring" in the First, "HUB SIAASING: A Knowledge-Based System 
    for Severe, Temporary Airline Schedule Reduction" in the Fourth,
    and "PI-in-a-Box: A Knowledge-based System for Space Science 
    Experimentation" and "The DRAIR Advisor: A Knowledge-Based System 
    for Materiel Deficiency Analysis" in the Fifth).

13) ARE THERE ANY TEXTBOOKS USING CLIPS?
----------------------------------------
    "Expert Systems: Principles and Programming" by Giarratano and Riley 
    comes with an MS-DOS executable of version 4.2 of CLIPS. The first
    half of the book is theory oriented and the second half covers
    rule-based programming using CLIPS. The second edition of this book
    will be available by January 1994 or shortly thereafter. It will 
    come packaged with an MS-DOS 386 executable of version 6.0 of CLIPS.
    The second half of the book has been updated to discuss features
    added to CLIPS since version 4.2. For more information, contact
    
       PWS Publishing
       20 Park Plaza
       Boston, MA  02116
       Telephone (800) 343-2204

    "Engineering of Knowledge-based Systems: Theory and Practice" by 
    Gonzalez and Dankel comes with a copy of CLIPS (version unknown).
    I haven't seen a copy of the book, so I don't know if the use of
    CLIPS is integrated with the book. There is an appendix which
    describes the CLIPS system. For more information, contact
    
       Prentice Hall
       P.O. Box 11073
       Des Moines, Iowa 50336-1073
       Telephone (515) 284-6761
       Fax (515) 284-2607    
              
14) ARE THERE ANY SPECIAL VERSIONS OF CLIPS?
--------------------------------------------
    HyperCLIPS version 2.0 integrates Macintosh HyperCard version 1.2 or 
    higher with CLIPS version 5.0. It is available through COSMIC (see
    question #2). The cost is $50 for the program and $15 for the
    documentation.
    
    wxCLIPS, developed by Julian Smart, provides a simple graphical front 
    end to CLIPS 5.1, and in addition contains a suite of extra functions  
    for creating GUI applications in CLIPS. wxCLIPS is available by 
    anonymous ftp from skye.aiai.ed.ac.uk (192.41.104.6). wxCLIPS is in  
    the /pub/clips5.1 directory.
    
    FuzzyCLIPS is an extension of CLIPS incorporating fuzzy logic. For more 
    information, contact Togai InfraLogic, Inc. by phone at (713) 480-8904
    or by fax at (713) 480-8906.

15) CAN CLIPS ACCESS EXTENDED MEMORY BEYOND THE DOS 640K LIMIT ON A PC?
-----------------------------------------------------------------------
    The executables distributed with versions of CLIPS prior to CLIPS
    6.0 were not able to access extended memory on IBM PC compatible
    computers. The CLIPS 6.0 PC distribution package comes with a DOS 
    386 executable and a Windows 3.1 executable both of which can 
    access extended memory. The DOS and the Windows 3.1  executable 
    requires a 386 microprocessor or better.

    A DOS 286 CLIPS executable with all features enabled that also uses 
    extended memory cannot be generated because of limitations on the 
    amount of static data (< 64K). By disabling features, an 286 executable 
    can be created which contains less than 64K of static data and also has 
    access to extended memory. Generating the executable requires the use of
    DOS Extender (either a separate product or one bundled with the compiler).
 
    A DOS 86 executable which has access to extended memory can not be 
    created, however it is possible to create a CLIPS executable that can
    run within the DOS 640K memory limit by disabling features.
    
16) CAN CLIPS BE COMPILED USING A C++ COMPILER?
-----------------------------------------------
    CLIPS was designed to support both the older Kernighan and Ritchie (K&R)
    C compilers and C compilers based on the ANSI C standard. C++ is not a 
    proper superset of ANSI C, and therefore some ANSI compliant code cannot 
    be compiled using a pure C++ compiler. Specifically, old style K&R  
    function declarations, which are used throughout CLIPS in conjuction with 
    both K&R and ANSI style prototypes, either do not compile or have different 
    meanings in C++. Thus, CLIPS can not be compiled using a pure C++ compiler. 
    Many C++ compilers provide an option which allows the use of K&R style 
    function declarations. In addition, it is also possible link CLIPS object 
    files generated using a C compiler with object files generated by a C++ 
    compiler.

17) DOES COOL STORE ITS OBJECTS AS C++ DATA STRUCTURES? 
    ARE THERE ANY PLANS TO CONVERT CLIPS TO C++?
-------------------------------------------------------
    CLIPS was written to conform to the ANSI C standard. It was also written 
    to be as compatible as possible with the older K&R style compilers.
    Since the object extensions of C++ are not part of the ANSI C standard,
    they are not utilized in the CLIPS source code. There are no plans to
    convert the CLIPS source code to C++.
    
18) HOW CAN I INTEGRATE CLIPS AS A C PROGRAM WITH OTHER C++ PROGRAMS?
---------------------------------------------------------------------
    The file clips-and-c++ available by anonymous ftp from hubble.jsc.nasa.gov
    in the directory /pub/clips/Documents describes how CLIPS source files compiled 
    as C programs can be integrated with C++ files compiled using a C++ compiler.

19) IS A DYNAMIC LINK LIBRARY AVAILABLE FOR THE WINDOWS VERSION OF CLIPS?
    HOW DO I USE CLIPS WITH OTHER WINDOWS 3.1 APPLICATIONS?
-------------------------------------------------------------------------
    A Windows Dynamic Link Library (DLL) for CLIPS 6.0 is not available.
    A DLL for CLIPS 5.1 is available by anonymous ftp from ftp.ensmp.fr
    in the directory /pub/clips/incoming. The file clips-and-windows 
    available by anonymous ftp from hubble.jsc.nasa.gov in the directory 
    /pub/clips/Documents describes three techniques for using CLIPS with other 
    Windows 3.1 applications (embedding CLIPS into your Windows application, 
    creating CLIPS as a DLL, or using Dynamic Data Exchange).

20) WHAT ARE THE ORIGINS OF CLIPS?
----------------------------------  
    The origins of CLIPS date back to 1984 at NASA's Johnson Space Center. 
    At this time, the Artificial Intelligence Section (now the Software 
    Technology Branch) had developed over a dozen prototype expert systems 
    applications using state-of-the-art hardware and software. However, 
    despite extensive demonstrations of the potential of expert systems, 
    few of these applications were put into regular use. This failure to 
    provide expert systems technology within NASA's operational computing 
    constraints could largely be traced to the use of LISP as the base 
    language for nearly all expert system software tools at that time.

    The Artificial Intelligence Section felt that the use of a conventional 
    language, such as C, would eliminate most of these problems. Although a
    number of tool vendors started converting their tools to run in C, the 
    cost of each tool was still very high, most were restricted to a small 
    variety of computers, and the projected availability times were 
    discouraging. To meet all of its needs in a timely and cost effective 
    manner, it became evident that the Artificial Intelligence Section would 
    have to develop its own C based expert system tool.

    The prototype version of CLIPS was developed in 1985. Particular 
    attention was given to making the tool compatible with expert systems 
    under development at that time. Thus, the syntax of CLIPS was made to 
    very closely resemble the syntax of a subset of the ART expert system 
    tool developed by Inference Corporation. Although originally modelled 
    from ART, CLIPS was developed entirely without assistance from 
    Inference or access to the ART source code.

    The original intent of the prototype was to gain useful insight and 
    knowledge about the construction of expert system tools and to lay the 
    groundwork for the construction of a fully usable tool. The CLIPS 
    prototype had numerous shortcomings, however, it demonstrated the 
    feasibility of the project concept. After additional development, it 
    became apparent that sufficient enhancements to the prototype would 
    produce a low cost expert system tool that would be ideal for the 
    purposes of training. Another year of development and internal use went 
    into CLIPS improving its portability, performance, and functionality.
    The first release of CLIPS to groups outside of NASA occurred in 1986.

    Further enhancements transformed CLIPS from a training tool into a tool 
    useful for the development and delivery of expert systems as well.
    Subsequent enhancements to CLIPS extended it beyond its initial 
    representation methodology of forward chaining rules by adding 
    procedural and object-oriented programming paradigms.

21) ARE THERE ANY LANGUAGES SIMILAR TO CLIPS?
---------------------------------------------
    CLIPS is an interesting example of technology transfer between the 
    government and private sectors. Syntactically, CLIPS traces its origins 
    to Inference's ART which traced the origins of its rule-based language 
    to OPS5. Later, CLIPS was used by Inference to develop ART-IM and by 
    The Haley Enterprise to develop Eclipse. In the early days of CLIPS
    development, porting an application from CLIPS to ART was fairly easy
    (although the reverse was not necessarily true if many of the advanced
    features of ART were utilized). In recent years, the features and
    capabilities of CLIPS, ART-IM, and Eclipse have diverged sufficiently
    that porting from one to the other is no longer a trivial task. Still,
    the basic syntax of their rules remains very similar and the flavor of
    the languages is more or less the same. For more information on either
    ART-IM or Eclipse, contact respectively Inference or The Haley Enterprise.

       Inference Corporation
       550 North Continental Blvd.
       El Segundo, CA 90245
       Telephone (310) 322-0200
       Fax (310) 322-3242
       
       The Haley Enterprise, Inc.
       413 Orchard Street
       Sewickley, PA 15143, 
       Telephone (412) 741-6420
       Fax (412) 741-6457
       
22) DID INFERENCE AID IN THE DEVELOPMENT OF CLIPS?
--------------------------------------------------
    Over the last several years, there has been a persistent 
    group of rumours to the effect that either Inference 
    developed CLIPS for NASA or that NASA used the ART source code
    to develop CLIPS. Neither of these statements are true. To set 
    the matter straight, there is not a single line of CLIPS 
    source code that was either written by Inference or given to 
    NASA by Inference. In addition, NASA never had access to the 
    ART source code.
    
    On the other hand, both ART-IM and Eclipse were bootstrapped 
    using the CLIPS source code. This became amusingly apparent
    when I discovered a bug that occurred in CLIPS, ART-IM, and 
    Eclipse, but not in ART. In addition, many of the C source 
    files that come with Eclipse retain the same file name as
    their CLIPS counterpart.
    
    It's irritating as a developer to not be given proper credit 
    for source code that you developed. It's even more irritating 
    when you see something like the following (taken from the 
    documentation accompanying Eclipse version 2.0e).

       "So NASA (who had the source code to ART) struck out to  
        develop its own ART clone with the key functionality of 
        data-driven pattern matching and syntax compatibility."

    Since the developer of Eclipse is the former chief scientist at
    Inference, who presumably is knowledgable about the relationship
    between ART and CLIPS, it is difficult to understand why he
    would include this rumor in his documentation without first 
    verifying its accuracy. The idea that a company would hand out
    their proprietary source code without any kind of written
    agreement and then allow it to be utilized to build a similar
    product is pretty ludicrous. 

    In any event, we're interested in setting the record straight
    about the development of CLIPS, so if you do happen to hear this
    rumour, drop us a line and let us know who you heard it from.

23) WHAT ARE THE FUTURE PLANS FOR CLIPS?
----------------------------------------
    After eight years of development and the release of version 6.0
    of CLIPS, our list of "must have" features has become very short.
    We haven't made any plans to begin work on the next major release
    of CLIPS. We will, of course, continue to maintain the CLIPS code
    and have minor releases when necessary to fix bugs or provide
    minor new capabilities. We intend to complete the CLIPS 6.0
    Architecture Manual and have it available sometime in 1994.
    
    It is likely that we will develop a Windows Dynamic Link Library
    and support Macintosh AppleEvents for CLIPS 6.0. The development
    of a class browswer for the machine specific interfaces is also
    a possibility.
    
    Likely new capabilities for the next major release of CLIPS would
    be temporal reasoning, inheritance by generalization, and 
    persistent objects.
    
    
                      


