Thanks muyuubyou and Brian for all your information.
I now understand clearly that I need to make sure my editor is working in
UTF-8, and that accented e (é) is going to have problems because it is not
part of the 127 characters that make up the original ASCII.
At present I haven't yet found an editor-type solution but I have made a
note that jEdit is one option.
When I get the problem fixed I'll let you know.
Thanks again for all your help. :-)
Hugh Prior