From time to time the content of the site has been updated
      In Autumn 2020 some pages were numbered, each with separated data and presentation layers
      It becomes a simple matter to preserve some old page names as entry points into the new navigation system
      Original page topics can be kept for interest, but smooth navigation of these pages becomes less likely.
 
 
 
 
 
 
 
 
 
 
 
Designed with care by John Hart