When you write a custom action of type "Custom" (based on the ple code that we deliver with QWP installer or your own code) the values can be set only within your custom actions and not within the ezEdit options.
Let's say that you have a list and qListForm that allows the user to add new item to the list. Your custom action is used in the form to pre populate a specific field "Field1" so when the user wants to add a new item the field "Field1" is prepopulated based on your businesss logic from your Custom action.
If you open the pleCustomActionsAndCustomLayouts project from the folder where you installed QWP you see the class pleFormInitializationAction : ICustomActionEx
and the method Perform thet gets executed on the page load event. This is a very powerfull feature when you want to have your code executed when the form loads or use the results form a previous cuastom action (see class pleCustomActionEx from teh same project).
Please let me know if you have any other questions.
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