A common request, when you're setting up a Search Service Application, is trimming results to documents only. Usually, it's not added value to show lists, libraries, folders or sites as search result items (for refinement, it's a completely different story).
Throughout the years, I've seen people achieving this in multiple ways (most commonly excluding *.aspx using crawl rules), but the right way of doing it is creating a scope and using either the
IsDocument or
contentclass properties.
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