Welcome to the forums from the Wiregrass! Because, for whatever reason, S&W didn't include those in the data they gave to Supica and Nahas who authored the book. Over the last few years, S&W has distanced itself from the collector community. They eliminated the historian position and cut off his access to company data. They dropped the authentication letters which forced the historian to move to the Historical Foundation for support. You can still get an historian's letter of authentication, but it comes from the Historical Foundation, not S&W. They mine the information they have but have no access to current S&W info.Thanks. Why would some prefixes not be listed. Newbie question I know.