The Axiom menu requires two files to load:

• aximenu.ma – the actual program. 
• aximenu.cfg – the configuration file that determines what is displayed on the Axiom menu when it loads in MicroStation. 

To load the Axiom menu, Bentley’s MS_DGNAPPS configuration variable must define it. That is accomplished when you perform an Axiom product installation. During installation, an axiom.cfg file is created, which contains a definition for MS_DGNAPPS that points to the location of aximenu.ma.
The axiom.cfg file is created in the Bentley application-level configuration directory: 
C:\Program Files (x86)\Bentley\MicroStation V8i (SELECTseries)\MicroStation\config\appl\

When MicroStation starts, it automatically loads any .cfg files found in the Bentley application-level directory, including axiom.cfg. The MS_DGNAPPS definition in axiom.cfg then causes aximenu.ma to be loaded, making the Axiom menu available for that MicroStation session.