The document doesn't justify this recommendation. Besides what Bob wrote, there is one other, legalistic, reason. Copyright law talks about notices of the form
Copyright YEAR1, YEAR2, YEAR3, ... ENTITY. They never talk about allowing ranges. I also heard from rms once that ranges were problematic because of stupid interpretations about the endpoints, i.e., whether the range was inclusive or exclusive. The simplest and best thing to do is avoid all the questions and murky areas, and just write out the years. karl
