By default, all EQUEL and DBMS server errors are returned to the EQUEL program, and messages are displayed on the standard output device. Using the iiseterr feature, you can define your own error-handling routine, which can display or suppress error messages. The iiseterr() function is not supported in all host languages. For more information, see the Embedded QUEL Companion Guide.

The program error handler must be declared in your program as an integer function, and declared as a parameter to the EQUEL routine iiseterr().

Avoid issuing any EQUEL statements within a user-written error handler, except for informative messages such as message, prompt, sleep and clear screen, and termination statements such as exit. If an error occurs in the error handler, there is the risk of infinite looping.