Don't remember seeing this posted before but NIST (National Institute of Standards and Technolog) has recently made available a study on the stability of optical dics. The study can be downloaded from this website http://www.itl.nist.gov/div895/gipwg/ -- Peter A. Kurilecz CRM, CA Richmond, Va [log in to unmask] List archives at http://lists.ufl.edu/archives/recmgmt-l.html Contact [log in to unmask] for assistance