xcall FILNAM, ch, filename
FILNAM returns filename when only the file channel is known. This is frequently useful in conjunction with error trapping, where the trapping routine identifies the file only by channel.
Parameters
ch (Num) [in]
the channel that the file is open on
filename (String) [out]
will return the filename (as specified in the open statement) corresponding to the specified file channel. If no file is open on that channel, filename returns a null string.
