Receiving Messages (the /MSGID= switch):
- By default most primitives do not forward their messages on to the macro.
- Most macros that send messages use the /MSGID= switch to enable messages.
  - Using /MSGID=MAIN will send the messages to the macro.
  - It is common to get messages from multiple primitives and send them all to the macro.
  - Messages sent to the macro go to the processMessage procedure.
    (This is covered on the next page.)
- Some of the commands that use the /MSGID= switch:
```
PLOT     LIST     LIST2     SOURCEDG
```

X-Midas Users Take Note:
The `/MSGID=MAIN` in NeXtMidas corresponds to `/MSGID=1` in X-Midas. This is because NeXtMidas allows IDs to be names, not just numbers.