1. A method of validating at least one of a plurality of systems, the method comprising: establishing a validation program template defining a style of input/output usable by a plurality of root functions to be performed by at least one of the plurality of systems; generating a validation program for each of the plurality of root functions based on the validation program template; establishing a markup language representation of each of the plurality of validation programs and corresponding root function; depicting a composite validation program for a composite function including a plurality of root functions using the markup language representation of the plurality of validation programs for the plurality of root functions in the composite function; and validating at least one of the plurality of systems by validating the composite function using the validation programs depicted in the composite validation program.