if the suffix was recognised, this is it. bang if suffix is unknown name of the format handler ([#io...]) that registered the file suffix association for this suffix. a filename to look at. only the suffix matters, not the rest of the filename nor the contents of the actual file. the file needs not exist. the folders don't matter. this does not even access any disks. the answer will either come out of outlet 2, or of outlet 1 then 0