-write @samp{1996--1998}; instead, write @samp{1996, 1997, 1998}.
+write @samp{1996--1998}; instead, write @samp{1996, 1997, 1998}. Do
+write each relevant year as a four-digit number. In the normal course
+of maintenance, you may come across copyright notices which omit the
+century, as in @samp{1996, 97, 98}---change these to include the
+century. However, there is no need to systematically change the
+notice in every old file.