1. A method of processing a computer source program, comprising the steps of: providing a data declaration extension syntax, wherein the syntax comprises use of DATE-FORMAT to identify the data declaration extension to a compiler and provides keywords for identifying one of a plurality of windowing techniques and provides fields for specifying ranges of years; receiving a plurality of programming language statements comprising a source program into a memory of a computer, wherein at least one of the received statements comprises a data declaration extension requesting a Year 2000 solution selected from a plurality of windowing techniques, and wherein the data declaration extension is in a format of the provided data declaration extension syntax; and compiling the source program into an object program in the memory of the computer, wherein the object program includes instructions for processing and/or invoking procedures on a data field associated with the extended data declaration according to the Year 2000 solution requested in the data declaration.