The modifier is 'X', the stream is 'Y'.
or A buffer cannot appear with the 'REFERENTS-ALLOWED' modifier.
or A referent cannot appear with the 'REFERENTS-ALLOWED' modifier.
Compilation continues but no compiled source code file will be saved.
Certain streams are not allowed to be opened, reopened, or written
to with certain modifiers. The only time the REFERENTS-ALLOWED modifier
is allowed is when a stream is opened as a file. This is the only
time it makes sense, since the referent values are not determined
until processing has finished; by this time the buffers and referents
can no longer be used, but the files are still around.