46. A method of integrating one or more declarative rules into a procedural computational system supporting object-oriented representation of data, the method comprising the steps of: executing, on a digital data processing system that comprises one or more digital data processors, a procedural sequence that comprises a plurality of procedural instructions, updating, upon execution of a procedural instruction that causes change to one or more data in an object, one or more other data participating in one or more declarative rules so as to maintain relationships imposed by said one or more declarative rules among said data, wherein said one or more other data (i) are those not changed by the execution of that procedural instruction, and (ii) are in said object and/or in other objects, where said rules are defined outside that procedural instruction, wherein updating of said one or more other data is performed by executing said rules on said digital data processing system prior to execution of any other procedural instruction in the sequence.
53. The method of claim 46 , wherein said one or more declarative rules are expressed in a tabular form, with the table columns (or rows) representing properties of related objects, and table rows (or columns) representing different values, or ranges of values.