The same problem with my Nikon book, the lens numbers do not always match what I actually have - it is all down down to the correct information being obtained from the manufacturer, which did not always happen - or a plain typographical error on behalf of the author of the book. Erwin was good but even the best make mistakes.

You could always write to Leica in Solms in Germany they have given me information like this before. Most who work there seem to be English speakers so there should not be a problem with communication