1. For a computer system interconnected to other computer systems on a network, a method comprising the computer-implemented steps of: (a) Providing a means for defining a Document Definition File (DDF), which is identified by a unique name and is a hierarchically organized plurality of elements, each element comprising an element type, element value, and a list of child elements; (b) Providing a means for processing requests from computer systems on the network, comprising the computer-implemented steps of: i. accepting a request for data from client systems, said request to include the identity of a DDF, and plurality of parameters, said parameters each comprising a reference to an element in the DDF and data; ii. copying said parameter data into said referenced element; iii. visiting each element systematically, for each substituting referenced element components with the actual value contained in said referenced element component, then performing a specified operation defined by said element; iv. transmitting the resulting data to the client; (c) Whereby a client computer system sends a request to said computer system identifying the DDF and input parameters, and the computer system reads the identified DDF, applies input parameters to said DDF, performs operations on every element of said DDF, and returns the resulting data set to the requesting client.