Prior to 3ds Max 2008, the Avguard Extension published by Larry Minton, the lead MAXScript developer at Autodesk, was available for free download. It has been used in many 3rd party scripts and is now completely incorporated into the 3ds Max MAXScript language, making the development and distribution of scripts using the functionality provided by the extension much easier.
If a script developed for 3ds Max 2008 or higher uses methods and variables from the Avguard Extension and the script has to be made compatible with 3ds Max 9 and earlier, please download the version of the Avguard DLX Extension for the corresponding earlier version of 3ds Max and make sure the method / variable still exists in that build and uses the same syntax.