A rule-builder interface is a user interface, usually a GUI or Web interface, that allows 'power-users to create business rules for various tools. These may be used to process incoming email; generate alerts when factory, credit, or billing oddities detected; and identifying most-likely customers, etc.
It can be an "expression builder" to build formula-like expressions, but there are other ways to express complex activity without "direct math". One has to know the domain and the user-base to select the best approach such that it's not "too techie" or "too mathy", yet approaches the same flexibility as direct math or programming. One can pull this off if they have a good understanding and feel for the boundaries of the domain. And it doesn't have to handle every situation, for custom programming is still needed for some situations. However, new domain concepts should be considered for integration into the existing RuleBuilderInterface if they keep appearing. It becomes a "new kind of Lego" in the rule building set.
Examples can be found in: