Micro Focus Enterprise Developer 2.3 for Eclipse > Programming > Mainframe Programming > PL/I Programming > Open PL/I User's Guide > Using Open PL/I > Using the PL/I Compile Time User Exit

Using the PL/I Compile Time User Exit

The PL/I compile-time user exit allows an installation to monitor compile-time messages. Every message that is issued by various components of PL/I is first subjected to the -f compile-time option. If the message is not suppressed by the -f option, it is presented to the user exit.

The user exit can:

Do nothing and allow the message to be processed 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 MPLIE00042E : Errors have ...
```
If the severity is lowered, the message will be shown as:
```
plisql1.pp (0,0) : Warning MPLIE00042E-: Errors have ...
```
The return code will be 4 instead fo 8.

If the severity is raised, the message will be shown as:
```
plisql1.pp (0,0) : Severe MPLIE00042E+: 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.
Suppress the message altogether. The severity of the suppressed message still carries through and participates in return code evaluation.

Note: The user exit API is a trusted interface and is running as part of the compilation process and therefore could affect its stability.

You can modify the provided user exit to suit your needs. It can be used to gather compile-time information for later or real-time analysis.

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

On Windows:

mfplx mfplicux.pli -dll -opt -nolaxdcl -vax -o mfplicux.dll

On UNIX:

mfplx mfplicux.pli -dll -opt -nolaxdcl -vax -o mfplicux.so

It must have an executable name of mfplicux (lowercase) and be placed in a directory that is on the search path (PATH on Windows, LD_LIBRARY_PATH on Linux and Solaris SPARC, and LIBPATH on AIX).