ANSWER: MASTR =
When the MASTR series of equipment was first introduced, they were the first GE-PRS products to be SOLID STATE. (A very big deal in those days.) This name was created by the following gentlemen: Dick Buesing, Bob Giorgi and Phil Dellwo.
The MASTR Series replaced the TPL Series (or Transistorized Progress Line).
Mark A. Cobbeldick KB4CVN