A magnetic tape cartridge, a recording system, and a magnetic tape drive are configured to, for example, guard against tampering with a write once overwrite protection pointer which allows a rewritable magnetic tape to be treated as write once. In one embodiment, the magnetic tape cartridge comprises a magnetic tape and a cartridge memory. The magnetic tape is configured to provide at least one overwrite protection pointer, the overwrite protection pointer identifying data to be protected from being overwritten; and the cartridge memory is configured to provide the at least one overwrite protection pointer, the overwrite protection pointer identifying magnetic tape data to be protected from being overwritten.