1. A method of generating a rules based end-user computer program on an interactive workstation having a display device, operation input means and a data store, comprising the computer-executed steps of: entering identities of two or more input data format screens in said computer program on an input screen of said display device which screen provides a number of actions that can be taken with respect to each entered identity including establishing a panel for an input data format screen and establishing a plurality of rule entry screens associated with each input data format screen; editing each panel for an input data format screen by means of the operator input means to define the formats of all permissible items of input data to the program; said editing step including creating and positioning fields for input data items within the panel layout and subsequently defining attributes of each input data item by means of a definition step which is separate from the step of creating and positioning of fields; storing the edited input data formats in the data store; displaying with respect to each data format screen a plurality of rule entry screens, each such screen in decision table format and including entry means for creating content in that format, each such screen being associated with one or more of the input data items; editing each rule entry screen using the entry means to define rules related to the associated input data items as decision tables logically relating conditions and actions by means of a pattern of logic values; storing the completed decision tables in the data store; and compiling the stored input data formats and decision tables to produce computer program code for run-time execution or interpretation.