What does VistA stand for?

VistA stands for Veterans Health Information Systems and Technology Architecture. (Yes. It has a silent H.) It is written in several computer programming languages ie: MUMPS, Delphi, and Java. MUMPS stands for the Massachusetts General Hospital Utility Multi-Programming System. (Yes it has a silent G and a silent H.) It's a tradition to have silent letters in our acronyms.What exactly is the Watermelon doing there?