The CUSTOM library is located in the $AU_TOP/res/plsql directory (or platform equivalent). The CUSTOM library you modify must replace the default CUSTOM library in this directory in order for your code to take effect.
After you write code in the CUSTOM procedures, compile and generate the library using Oracle Forms. Then place this library into $AU_TOP/res/plsql directory (or platform equivalent). Subsequent invocations of Oracle Applications will then run this new code.
Warning: If there is a .plx (compiled code only) for a library, Oracle Forms always uses the .plx over the .pll. A .plx is only created when you generate a library using the Oracle Forms generator (using the parameter COMPILE_ALL set to Yes), not when you compile and save using the Oracle Forms Designer. Therefore, either delete the .plx file (so your code runs directly from the .pll file) or create your own .plx file using the Oracle Forms generator.
The specification of the CUSTOM package in the CUSTOM library cannot be changed in any way. You may add your own packages to the CUSTOM library, but any packages you add to this library must be sequenced after the CUSTOM package. To ensure that your packages remain sequenced after the CUSTOM package even after a conversion from a .pld file, when program units are alphabetized, we recommend you name your packages with characters that come after C (for example, we recommend you name your own packages with names that begin with USER_).
The following considerations and restrictions apply to the CUSTOM library and any libraries you attach to CUSTOM:
You should exercise caution when changing any properties or values of items in the form from which CUSTOM logic is invoked. The CUSTOM library is intended to be a mechanism to augment Oracle code with your own. Using the CUSTOM library to alter Oracle code at runtime may bypass important validation logic and may jeopardize the integrity of your data. You should thoroughly test all logic you add to the CUSTOM library before using it in a production environment.
If you use Zoom or the CUSTOM library to invoke forms that you have developed, those forms must adhere completely to all of the Oracle Applications coding standards.
Attention: To invoke another form, use the function security routines. Do not use CALL_FORM since the Oracle Applications libraries do not support it.
Additional Information: Oracle Applications Developer's Guide
See: Events Passed to the CUSTOM Library
When to Use the CUSTOM Library
CUSTOM Library Package Procedures
Support and Upgrading
Example of Implementing Zoom Using the CUSTOM Library