G11B 13/045

Recording simultaneously or selectively by methods covered by different main groups {among [CPC: G11B3/00], [CPC: G11B5/00], [CPC: G11B7/00] and [CPC: G11B9/00]}; Record carriers therefor {not otherwise provided for}; Reproducing therefrom {not otherwise provided for } magnetically {or by magnetisation} and optically {or by radiation, for changing or sensing optical properties combined recording by magnetic and optic means}