The future of LT-Extender is : BRICSCAD V9 !
 
This might be suprising for many users and developers - therefore we would like to document our conviction and our opinion - and simply, the facts ! - to all our users, developers and interested parties here, to point out the real and true alternative for AutoCAD LT and LT-Extender.
 
Some (explaining) details just ahead :
Since 2006 are we working together with the Bricscad team for integrating our AutoLISP-Interpreter into Bricscad V8. As two independent developer teams we have exchanged ideas and worked out solutions for the ARX -compatible C/C++ Interface (called BRX). And "last but not least" the Bricscad team appreciated and consulted a lot our expertise regarding the common and particular AutoCAD compatibility.
 
For a long time (at least since 2002) we are carefully watching the area of so-called "AutoCAD-Clones" - to be prepared for the time after LT-Extender. Especially during the last 3,4 years, there were some most interesting and exciting developments in this area (keywords IntelliCAD, DwgLib, OpenDesignAlliance) which finally lead to the current situation : having Bricscad V9 as a real alternative for AutoCAD and AutoCAD LT in the CAD market.
 
So we will document and explain our opinion and our conviction here – as objective and comprehensive as possible.
 
Now, why especially Bricscad ?
To speak about the main, simple reason : because Bricscad, in the world of those AutoCAD compatible CAD sytems, is currently the only (and indeed, the very first ever) system which really provides all those  programming interfaces (APIs), as provided from AutoCAD, with an unrivaled, high level of compatibility. And because Bricscad, for especially this reason, provides application developers with a real alternative to adopt their applications (designed for AutoCAD) with minimum afforts for an AutoCAD independent platform.
 
Bricsys provides a comprehensive documentation and overview on implemented programming interfaces (APIs) with its Bricscad-Developer-Reference.
 
CAD users, applications and the application developers are respected as the nessecary unity which is nessecary for the success of the Bricscad CAD system, as well for the success of CAD users and application developers.
With the decision, to restart the development of Bricscad V8, there were great opportunities to redefine the goals of V8 and to overcome old restrictions and limitations.
 
The main point of the new Bricscad concept (in our opinion) is this :
The new Bricscad is designed to address the maximum and perfect AutoCAD compatibility - for all parties : for the CAD users with provided commands, functions and system variables, and for the application developers and their applications with the unbeaten level of compatibility in all programming interfaces.
All available IntelliCAD based systems (as well as Bricscad also) do provide a good Look & Feel - a user interface as known from AutoCAD; they all are more or less following the usual Windows design guides and rules ... so for AutoCAD users, there is virtually no difference in using the interface at all; the main advantages provided by Bricscad are those programming interfaces (APIs) for application developers.
 
And now, for the details
 
As already codumented here - the compatibility of application programming interfaces (APIs) - and even the compatibility of commands, options and system variables - is one of the most important details (and one of the most important development goals) for the new Bricscad generation. Therefore we would like to have a closer look insight here; there are many and comprehensive informations at Bricscad website as well; we will provide links here as well, were appropriate.
 
It is the expressed and clear target for Bricscad development to provide (nealry 100%) sourcecode compatibility for all supported APIs - this means, that existing applications (designed for AutoCAD) will not need to be adjusted in their sourcecode, but rather immediately work with Bricscad (ADS/ARX based applications will only need to recompile, ideally); if nessecary, only very few adjustements in sourcecode needs to be done only, with veryless efforts.
 
So Bricscad is able to provide the main advantage, that developers no longer need to manage different sourcecodes for AutoCAD and Bricscad - but will be able to manage any potetial difference (if ever) in a single sourcecode ! It is this most important detail, which gives developers the real freedom and effectively allows application developers to provide  their application for Bricscad as well ... one sourcecode for all CAD systems !
 
Programming Interfaces (APIs) in Bricscad
 
DCL user interface :
this is available without any problem, and can be used and accessed by both AutoLISP and ADS/SDS applications
additionally, Bricscad provides resizable DCL dialogs and ToolTips for buttons, images, listboxes etc. (both improvements do not break AutoCAD-compatibility !)
 
ADS/SDS:
 this interface has been available since a long time, and can be used as well. The SDK (Software Development Kit), as provided by Bricscad, also includes Header files which will automatically redefine any "ads_xxx" function name to appropriate "sds_xxx" function name, so developers will not need to care about these details.
 
VBA / VB / COM:
 Bricscad offers a completely AutoCAD compatible COM interface - this means, the COM object model itself is compatible with AutoCAD' COM object model. Additionally, Bricscad also offers binary compatibility regarding the *.dvb files and fileformat. As result of this high level of compatibility, Bricscad is able to load and run those *.dvb files which are designed for AutoCAD, and in turn, those *.dvb files created with Bricscad can be loaded and run inside AutoCAD !
Tip: the only code adjustement(if nessecary) :
The main (root) COM application object as provided by Bricscad is named "BricscadApp.AcadApplication", while AutoCAD uses "AutoCAD.Application"; to overcome the drawbacks of this difference, Bricscad offers a configuration switch in "Settings" dialog : Program Options => System => "COMAcadCompatibility = 1"; when this option is activated, Bricscad additionally also registers as "AutoCAD.Application" with the COM system, and therefore, no VB/VBA/COM sourcecode adjustement is nessecary.
 
If there is no AutoCAD installed on the computer, Bricscad will detect this, and will automatically registeres itself as "AutoCAD.Application" as well.
 

AutoLISP:
Starting with the new Bricscad V8, our AutoLISP-Interpreter (originally designed for LT-Extender, since AutoCAD LT 2004) has been integrated into Bricscad - and has been evolved into a very stable, highly performant and highly compatible Lisp engine. Therefore, Bricscad is able to provide the best platform for AutoLISP based applications, no known compatibility issues or problems.

main features of our "LispEx“ AutoLISP-Interpreter for Bricscad:
 fully supports standard AutoLISP language set
 fully supports VisualLISP language set (vl/vlr functions)
 fully supports the COM based VisualLISP language set (vla/vlax functions)
very high performance - compared with both AutoCAD and IntelliCAD based systems (see and try our LispBenchmark)
FAS and VLX fileformat is not yet supported by "LispEx" - these fileformats use a particular lisp sourcecode encryption; to ensure Lisp code safety for developers, Bricscad can load encrypted Lisp file produced by both our DEScoder.exe as well as produced by Bricscad's own EncryptGui.exe utility; those encrypted Lisp files should be named as *.des.
 
DRX (Dwgdirect Runtime eXtension):
Another C++ programming interface is provided by that DwgDirect CAD engine (by OpenDesignAlliance) used by Bricscad - this interface can be used by application developers, but the difference to ARX are significant, which requires and enforces a complete rewrite of any ObjectARX based sourcecode; please see this ARX/DRX comparision ...
 
BRX – the ObjectARX-sourcecode-compatible „Bricscad Runtime eXtension :
This C++ programming interface is (currently) unique and exclusively available only with and for Bricscad - based on the DRX API, Bricscad offers a completely ARX sourcecode compatible interface to all developers. Ideally, application developers will only need to recompile their application, using the BRX SDK ... even though this BRX interface is not yet finished (and therefore, can cause a few code adjustements still), it gets better and more complete with every day, based on developers' feedback - so it is only a question of time until fully completed, or at least, covering 95% of all ObjectARX based sourcecode.
A very good explanation of the BRX / DRX Systems is provided by Bricsys as well.
 
In our estimation, it is especially this BRX programming interface, which is the major key for success, to attract application developers to the Bricscad platform - and all the feedback from developers, porting their ARX based applications using BRX, clearly prove this.
 
For all the above mentioned reasons, it should be clear now, that it is our real pleasure to contribute to the Bricscad development - we do not only care for our "LispEx" Lisp engine, but also contribute especially to the BRX system development. This way we can provide all our experience from 15 years of AutoCAD application development, but also our experiences from 7 years of LT-Extender development.
 
Programming Interfaces in IntelliCAD based systems
 
From our experience, and as well as from many users and developers feedback, there seems to be some confusion and uncertainty around the ARX and DRX, but also around the VB/VBA/COM programming interfaces - therefore, we would like to provide some clearity here.
 
IntelliCAD has a quite long development history, and for this reason, it has a number of proven, safe and stable programming interfaces : LISP, DCL, SDS.
 
Lisp:
We are really proud to provide our AutoLISP-Interpreter "LispEx" exclusively for Bricscad - combining a stunning performance with an unrivaled compatibility; our LISP engine is not available in any other CAD package.
 
COM/VB/VBA:
The COM object model provided by Bricscad is fully AutoCAD compatible - even a binary fileformat compatibility is provided with the *.dvb files, as used by both AutoCAD and Bricscad. Currently, Bricscad's COM object model is not yet completely finished - a few interface classes are not yet implemented, but will follow in short terms.
 
ARX / DRX / BRX:
Bricscad exclusively offers the BRX SDK - this BRX system is not only unique and exclusive in the world of AutoCAD compatible clones - it is especially fully ARX sourcecode compatible ! This offers all ARX application developers (for the very first time ever !) the great chance to use their existing ARX application sourcecode - and to provide a Bricscad version directly by a simple recompilation (ideally, but sometimes few sourcecode adjustement is still nessecary, until BRX is completely finished), and to continue development with a single sourcecode stream only, for both AutoCAD and Bricscad.

Another C++ programming interface is provided by the DwgDirect CAD engine (by OpenDesignAlliance) used by Bricscad - this interface can be used by application developers, but the difference to ARX are significant, which requires and enforces a complete rewrite of any ObjectARX based sourcecode.
 
At Bricscad/Bricsys websites you will find a very informative and clear BRX / DRX comparision.
 
And finally : some personal words from our side …
As hard as this decision to terminate the LT-Extender-Software really was for us, and as much as we really regret this – there are some positive aspects as well :
1. the LT-Extender software (with AutoCAD LT) is no longer a competitor for Bricscad,
and we can fully concentrate our complete development resources on Bricscad development
2. the termination of LT-Extender could be final the trigger for many CAD users and for many application developers to give Bricscad a real chance and to provide the applications for Bricscad.
 
Naturally, we will offer and provide any suitable support, assistance, help, for all users and developers, in any requested and desired way, around the subject of "Bricscad" - this is not only promised, this is guaranteed here !
 
Of course, we really hope that as many users and developers as possible will give Bricscad a try ... maybe, right now, and/or another try after few months (as Bricscad gets better with every day !), and take Bricscad into account in their plannings. But at least, we are sure (and hope, we did verify here, why we are convinced) :  if there is an alternative to AutoCAD today - then it is Bricscad. But wether Bricscad will become the main counterpart - this depends on the CAD users and especially on the application developers ... we will provide all our best, in the interests of all.