Hey all, don't mean to double post but I didn't get any responses when I asked in the General Discussion area. I have a Brilhart Tonalin Personaline alto piece with a 5 digit serial number and the opposite side stamped "S4", except that it's upside down in relation to the serial number. Does anyone here know what the "S" in "S4" means, and why this would be stamped upside down?