>>60653 Dept. of State FOIA reading room search for "F-2015-00940". (Use quotes in the search box or there will be a shit ton of information to sift.)
Turns up in one of the annual reports of FOIA activity as "closed". However, both the name of the requestor(s) AND the subject of the request is redacted. Requestors names are redacted for reason (b)(6) .
Go on to the National Archives redaction code list and b(6) definition:
3.3 (b) (6) Reveal information, including foreign government information, that would cause serious harm to relations between the United States and a foreign government, or to ongoing diplomatic activities of the United States.
Not sayin' F-2015-00940 is the actual meaning, but having spent "Lon tine" poking around the DOS reading room, the number was immediately recognizable.
https://foia.state.gov/search/Results.aspx?searchText=%22F-2015-00940%22&beginDate=&endDate=&publishedBeginDate=&publishedEndDate=&caseNumber=
https://www.archives.gov/declassification/iscap/redaction-codes.html