This policy setting controls whether Office 2010 applications load any custom user interface (UI) code included with a document ...

This policy setting controls whether Office 2010 applications load any custom user interface (UI) code included with a document or template.  Office 2010 allows developers to extend the UI with customization code that is included in a document or template. 

If you enable this policy setting, Office 2010 applications cannot load any UI customization code included with documents and templates. 

If you disable or do not configure this policy setting, Office 2010 applications load any UI customization code included with a document or template when opening it.