1. A method for modifying data according to configurable criteria, comprising: storing a plurality of programmably configurable protocol descriptions, the programmably configurable protocol descriptions, the programmably configurable protocol descriptions each including a protocol control record and at least one field sub-record for defining at least one data modification; storing a program for controlling a data modification function to be executed by a processing unit, the program including instructions for causing the processing unit to selectively retrieve the at least one programmably configurable protocol description and to vary the execution of the data modification function based upon the at least one retrieved protocol description; delivering to the processing unit the program for controlling the data modification function; delivering to the processing unit the data; and enabling the processing unit to execute the data modification function.