You seem to have requested the nonexistent URL http://www.eskimo.com/~scs/cclass/cclass.htm . The correct URL is http://www.eskimo.com/~scs/cclass/cclass.html. Please make a note of it.
[Obligatory philosophical rant follows; stop reading now if you're sensitive about such things.]
Contrary to peopular belief, Microsoft does not own or set the standards for the Internet. Real computers have allowed long and arbitrarily-spelled filenames for decades. (Furthermore, URL's have no necessary relationship with filenames at all.)