What is VISTA made of?
The OSEHRA Forum project is about upgrading how VISTA is developed, distributed, installed, and version-controlled. This makes a lot more sense if you know know what VISTA's made of. It's different from software written in other programming languages, which changes how you can manage it.
The VISTA server software - which is most of VISTA - is written in MUMPS, the only major programming language created specifically for writing medical software. OSEHRA Forum focuses on the MUMPS parts of VISTA.