Apparently the "0 - Don't send" choice is used when $redirect=301 (or 302) returns a blank page.
Since I get a blank page in the browser when I use that $redirect=301 setting, I am trying the "0" setting - "Don't send a 301/302 header, my webserver does this. (Enable this if 301/302 results in an ISE or blank page)" setting.
It works- there is a redirect and no blank page. The problem is that it is a 302 redirect which is not search engine friendly so I would prefer to use a 301.
What I need to know is how I go about making that change so using the "0"' setting results in a 301 redirect instead of a 302.