When you implement the limitation in the LOV-query of the item, the limitation will also be applied to the selected values. Usually this is not the desired behavior.
The plugin attributes are the shuttle item and the select item. The plugin needs to know the select item to disable submit when enter is pressed.
You can see the plug-in in action on:
As usually you can find the plugin on apex.world
Source Article from http://dickdral.blogspot.com/2017/04/oracle-apex-plug-in-for-restricting.html