For Test_System a good understanding of the AXE10 “blocks” (RE, REICH, PREA, REIBA, REIAA, FOAM, etc..), MML commands, PLEX and ASA really helps you to get upto speed with Test_System. In the past (circa 1990s) patches could be deployed on a live switch using Test_System. In fact, “punching” variables using “SET (T)VAR” and
“PRINT VAR” was a common practice. At the time there was other switches that was based on BTCoral66. Periodically, this required a decompiler (DCD) to ensure that the executing code and data was correct.