FIELD: method and machines for producing card-shaped data media. SUBSTANCE: proposed method includes at least one procedure requiring definite type or quality of data medium or its definite position, and/or position implying changing data media to such extent that it becomes unrecoverable or its recovery needs additional expenses. Prior to or after this procedure data medium is subjected to optical test whereupon its further treatment is effected depending on results of this test. EFFECT: enhanced yield. 16 cl, 8 dwg
