i've found that, differently from listTables([$schema]), this function doesn't default to current schema, if omitted, but instead select every FK based on the table name.
It works fine if schema is specified, otherwise if tables with same name are present in different schemas, their references will be mixed up with no-sense results, like a single reference with the same column declared twice or more in the local or referenced column list. I cannot figure out a scenario where mixing schemas FK can be considered usefull o_O, so i suppose schema has to be mandatory or defaulted to current.
Is this the expected behaviour or a simple distraction? :)
To have a test, create a simple two table DB with a FK between them, dump and restore the DB with a different name but keeping tables intact: describeReferences($table) should now give you funny results as to me!