HOME LOCAL PURPOSE 
 

This criterium has little to do with the sites themselves and more to do with what YOUR purpose is to collect them. If you want to list as many sites on particular topics as possible to help your patrons on homework assignments then the Design consideration may take a back seat, as demonstrated in Homework Center at Multnomah County Library.  If, however, your purpose is to select the VERY best sites out there, then you might be highly discriminating and collect only few sites.  See the example of Notable Children's Websites below.

 
Authority
Appendix