Changes the severity of warning or error messages.

  The default is that compiler diagnostic warning messages and
  standards checking messages have a severity of warning, or
  /SEVERITY=(WARNINGS=WARNING).

  ERROR
    Specifies that all warning messages are to be issued with ERROR
    severity.

  STDERROR
    Specifies that if /STANDARD is in effect and diagnostics
    indicating non-standard features are issued, the diagnostics are
    issued with ERROR severity (the default is that these are
    informational).  All other warning messages are issued with
    WARNING severity.

  WARNINGS
    Specifies that all warning messages are to be issued with WARNING
    severity.