A Question About actual resource lookup process

Hi There ;

During the study in silverlight I have encountered an issue. In that link (http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.resources%28v=vs.110%29.aspx) there is an paragraph:

Note that this property returns only the resource dictionary declared directly within that element.This is different than the actual resource lookup process, where a child element can access any of the resources defined in each parent element, searching recursively upwards.

What is the thing that described with underlined, Could you please explain?

Thanks in advance.