I was reviewing some code submitted by a developer and I came across the following in a SELECT clause
{fn IFNULL(fieldname,'')}
It is obviously the same as COALESCE and ISNULL but what surprised me was that it worked without alteration.
I can't find anything about {fn ....} in BOL but I am curious as to why T-SQL is able to process it and, as it isn't documented, what else is hidden