Abstract: A multi-classification information security method to prevent information in a computer information system with one of a plurality of security classifications to be written onto an input/output means with a non-compatible security classification. The method may also prevent information with one of a plurality of security classifications from being accessed by a user with a different classification. A detector means located in the computer input/output device detects the classification of the input/output means which is indicated by color or bar code indicia located on the input/output means. This input/output means classification is compared with the classification of the information. When the classifications correspond, information can be written to the input/output medium.