Hello,
it depends on what you mean by 'mount'.
If 'mount' is taking cartridge to put into a drive, the answer is no.
If 'mount' is taking cartridge to put into a drive, then reading the label and informing Networker about this operation (updating drive status), the answer is yes.
By default, Networker physically 'mounts' the tape in the drive before labelling, but don't update the drive status as 'mounted'.
Labelling is (re)writing a label on tape and writing a double EOT (End-Of-Tape) immediately after, thus preventing drive accessing after this 'line'.
Denis