1. In a rule processing system, a computer-implemented method of providing selection advice for selecting desired specifications of a product or service characterized by a Zero-suppress Decision Diagram (ZDD) rule model having one or more Include or Exclude rules, the method comprising: displaying on a monitor multiple attributes having multiple enumerations that identify possible specifications of the product or service; selecting, via an interface, multiple alternative enumerations of at least one attribute; determining the selection advice by indicating at least one of the selected multiple enumerations of the at least one attribute non-compliant and by indicating at least another of the selected multiple enumerations of the at least one attribute that, if changed, will result in all other of the selected multiple enumerations of the attributes simultaneously compliant responsive to the selecting; where the determining includes: forming a MakeSelectionTermForGroup (MSTFG) ZDD tree with nodes respectively associated with attributes having a single selected enumeration; forming a ZDD tree having nodes respectively associated with selected enumerations for each attribute having multiple enumerations selected including the at least one attribute; sequentially intersecting the MSTFG ZDD tree with each of the ZDD trees formed for the at least one attribute having multiple enumerations selected to generate a final MSTFG ZDD tree; and combining the final MSTFG ZDD tree with the one or more Include rules to produce a result; and using the result to choose a product or service having desired compliant specifications.