Ref T9360. This adds ability to search posts by blog(s) and by type better.
Probably just blog= works, too.
(This would become "blogPHIDs" with the change below.)
Maybe use blogPHIDs as the key, and 'blog', 'blogs', 'blogPHID' as the aliases.
Minor, but maybe "on certain blogs" instead of "with certain blogs"?
Yeah, the "aliases" thing is basically just "anything a somewhat-reasonable user might try to type into the URL to select this field", and the "key" is what we actually store in the database.
(In some apps it also does "things we used to make you type into the URL that should probably still keep working".)