All databases start with an ``ident'' record which contains a title string that identifies the model, the current local units (eg, mm, cm or inches) of the model, and a database version identification number. As noted, all numerical information in the database is stored in the fixed base unit of millimeters, and all work (input and output) is done in a user-selected local unit. The user can change his local unit at any time by using the units command. This way of handling units was selected to free the user from worrying about units conversion when components are drawn from the ``parts bin''.