An aside, but Y100K-limited fixed-length years are dumb. They don’t fix a Y10K problem, because untruncated variable-length years don’t have a Y10K problem. The Y2K problem was caused by truncated 2-digit years with an assumed two-digit prefix, and the problems when the assumed prefix became an incorrect assumption.

Its true that software that only reserves four digits for years becomes a problem in Y10K, but fixing that internal representation problem shouldn't have any effect on presentation, and if it does “5 digits fixed” presentation is a soft indication of the most short-sighted possible solution.