In this database design, a history of the design changes can be maintained to assist the designers while developing the prototype robot. This history includes the following:
The design can be added to the design history upon the user request. This is accomplished by adding new records to the database files with a version number specified by the user. For example, if the user wants to add the current design status to the design history, this is accomplished by clicking on the ``history'' button, and typing the version number (e.g., ``design-dec-9-93''). A copy of the necessary records from the current design then will be added to the files.
The retrieval of any design from the design history requires the user to input the version number, and then the information about this design will be displayed. The file ``history'' shown in Figure 37 contains some information about the design such as the design number, the starting date, the finishing date, and the platform used for that design.