How a diagnostic is identified (§2.1.1.3)
Microsoft C produces error messages in the form:
filename(line-number) : diagnostic Cnumber message
where filename is the name of the source file in which the error was encountered; line-number is the line number at which the compiler detected the error; diagnostic is either “error” or “warning”; number is a unique four-digit number (preceded by a C) that identifies the error or warning; message is an explanatory message.