XML Content and Actions : change layout set for iView

Hello,

I need to modify the layout set parameter for around 50 iViews for which it is left to blank. I thought that with an xml export I would just have to change the parameter "rndRootLayoutSet" and then reload the xml.

But I don't find the parameter in the export result. Looking at the document <b>How to automate content creation via XML</b> I see that I can use actions for deleting content or assigning role ....

So I search how to add an attribute to iViews with the same prefix.

Does someone knows how to do this.