Abstract: A diagnostic instrument or data acquisition apparatus having a database for storing communications interface specifications and other properties of diagnostic attributes (e.g., sensor measurements or operating conditions) outputted by various classes (models or versions) of equipment to be tested. The database records include a first field identifying a class of equipment, a second field identifying (e.g., by name or description) a diagnostic attribute whose value is outputted by that class of equipment, and a third field. The third field can specify an ID (e.g., physical signal line, physical address, or logical address) that enables a diagnostic apparatus to retrieve the value of the attribute identified by the second field from the class of UUT equipment identified by the first field of the record. Alternatively, the third field can identify the communications interface at which the diagnostic attribute is transmitted.