The GeneXus standard classes are a set of routines, written in native code, that are referenced by the generated code. As an example, the code to send an e-mail is not generated in every object that sends e-mails. It is "packed" as part of the Standard Classes and referenced by the generated code.
Every GeneXus Generator has its set of Standard Classes.
Standard Classes in an executable format are distributed on every GeneXus version and are automatically installed.
Standard Classes source code is _not_ distributed with GeneXus for many generators (see below). If you want to take a look at the source code, you can download it from the GeneXus Assembla space. NET standard classes can be reached from http://svn2.assembla.com/svn/genexus_standard_classes/ and Java standard classes from https://github.com/genexuslabs/JavaClasses
You can download (if required), change and redistribute the Standard Classes source code. For details see the license information and https://github.com/genexuslabs/JavaClasses/blob/master/LICENSE
Depending on the generator, those routines are packaged differently.
Refer to https://github.com/genexuslabs/JavaClasses#how-to-compile and https://github.com/genexuslabs/JavaClasses#modules
The already packaged routines are located on the <GeneXus Installation>\gxjava folder as gx*.jar.
The C# generator provides the GeneXus standard routines in the GxClasses.dll assembly located on the <GeneXus Installation>"gxnet\bin folder.
In order to execute any iSeries (Cobol|RPG) program, you need to install the GeneXus iSeries Library; the standard GeneXus routines used by the GeneXus Cobol and RPG programs.
The GeneXus Standard routines for Android are packaged on the FlexibleClient project located on the "GeneXusInstallationFolder"\Android\FlexibleClient\ folder (java source files) which is copied to the target generation folder KnowledgeBaseName\ModelName\mobile\Android\FlexibleClient during the generation phase. This project depends on other projects located on the UserControlLibraries folder.
The GXFlexibleClient framework is the iOS GeneXus standard classes deployed as a framework which is referenced in your xCode project. You will notice it is copied and installed in the MAC machine during the compilation process.
External utilities used by GeneXus generated applications