I am not sure whether I understand you correctly. You can pass values to the UserControl you load in the RadDock in the standard ways - adding a property to the UserControl which you can access from the page in which you load the control, using the Session object to pass the needed values and etc and this does not depend on the RadDock control itself.
If you want to associate the information displayed in the dock with the RadDock control and save it in its state you can use the dock's Tag property. It accepts a string as a value, however, you can serialize and store more than one value as a string separated by semicolons, for example, and retrieve the values afterwards splitting this string, e.g.:
|RadDock1.Tag = "string1;string2";
|string strings = RadDock1.Tag.Split(';');
In case the above explanation does not answer to your exact question, please, describe in more details what you want to achieve and what are the difficulties you encounter. We will be glad to help you.
the Telerik team
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