] is a global object assigned to be a list of the names of messages generated during the processing of the n
Only messages that are actually output are included in the list MessageList[
The message names in the list are wrapped with HoldForm.
] includes messages generated both by built-in functions and by explicit invocations of Message.
See the Mathematica book: Section 2.8.21, Section 2.13.1.
See also: $MessageList.
This returns $MessageList (the value of which is assigned to MessageList[n]), which gives a list of the messages produced.
Sqrt::argx: Sqrt called with 3 arguments; 1 argument is expected.
Exp::argx: Exp called with 2 arguments; 1 argument is expected.
The message names are wrapped in HoldForm to stop them from evaluating.