An access key is required for operation of features of a medical instrument. Acontrol program is used to control access to the operating features of themedical instrument. All programs of the medical instrument are validated foroperation of any and all of the features of the medical instrument eitheralone or in any combination. However access to use of those features orcombinations of features of the medical instrument requires an access key thatis recognized by the control program. The pump may be usable in a basicoperational configuration without entry of any access key； however, moreadvanced features will be disabled unless the operator enters a correct accesskey to enable one or more of those features. Operator input for enabledfeatures will be accepted by the instrument but operator input for disabledfeatures will not be accepted. Disabled features are not displayed, nor isinformation about them displayed. By means of the invention, the medicalinstrument and all of its control programs are completely validated for alluses and modes of operation during manufacture； however, users are restrictedfrom use of certain features by means of the requirement for an access key.
