According to an old BC release post on the BC blog here:
It mentions the following:
However in the official forum release notes it doesn't appear to mention it at all:
Was this feature ever implemented and if not is there any way we can exclude WebApp items from search engines and/or BC auto sitemap.xml?
If you use a web app and do not have a detail view you tick the option in the web app settings (Disable detail pages). Which causes thw web app to not have that layout, not generate a url and not be indexed. This was what was added and I believe that is what that refers too. BC's wording has never been a strong point.
There is no "Exclude from search" option on web apps with a detail page like on pages but you can add the meta to the detail layout for that or per page through the page description if you want too.
Ah ok. Thanks for clarifying.