Micro Focus Enterprise Developer 3.0 for Visual Studio 2017 > Programming > Mainframe Programming > PL/I Programming > Open PL/I User's Guide > Using Open PL/I > Using the PL/I Message User Exit

Using the PL/I Message User Exit

The PL/I message user exit allows an installation to monitor compile-time and run-time issued messages. Every message that is issued by various PL/I components is presented to the user exit. If it is a compiler-issued message, it is then subjected to the -f compile-time option.

The user exit can:

Do nothing and allow the message to be processed by PL/I as is.
Change the severity of the message one severity level up or down. Note that I-level (severity level 0) cannot be lowered and U-level (severity level 4) cannot be raised. Thereafter, the message will be issued as is (with the same exact text, including severity level) with a "+" (for raised severity) or "-" (for lowered severity) indication but the new severity will be used for return code purposes.
Example:
```
plisql1.pp (0,0) : Error MPLIE00042W : Errors have ...
```
If the severity is lowered, the message will be shown as:
```
plisql1.pp (0,0) : Warning MPLIE00042W-: Errors have ...
```
The return code will be 4 instead of 8.

If the severity is raised, the message will be shown as:
```
plisql1.pp (0,0) : Severe MPLIE00042W+: Errors have ...
```
The return code will be 12 instead of 8.

Upon return from the exit, the message is not subjected to the -f option. Note the + or - sign that follows MPLIE00042W as this indicates the change in severity.
Suppress the message altogether. The severity of the suppressed message still carries through and participates in return code evaluation.
Important: We strongly recommend that you do not suppress run-time messages.

Note: The user exit API is a trusted interface and is running as part of PL/I and therefore could affect the stability of the run-time system and of the compiler and other components involved.

Enterprise Developer provides a skeleton default user exit that you can modify to suit your needs. It can be used to gather compile-time information for later or real-time analysis. Ensure that your modified user exit either takes precedence over or replaces the provided skeleton user exit.

The compile-time user exit should be built as follows:

On Windows:

mfplx mfplictx.pli -macro -dll -native -opt -nolaxdcl -vax -pp mfplictx.pp”

It must have an executable name of mfplictx (lower case) and be placed in a directory that is on the search path (PATH on Windows).