I feel like at some point I heard there was a search API for the 
Proquest content/database platform.

I can find no evidence of it on google, but that's not really unusual 
for most of our vendor's apis.

Does anyone know if such an API exists, usable by Proquest customers, 
and if so how to get more info about it?

I am particularly interested in a search API to the Proquest 
Dissertations & Theses database, but most Proquest content seems to be 
on a standard consistent platform, so I imagine any API's that exist 
would not be special to that one database.