Yamaha serial and model number in dots

I am returning to the sax after a number of years and have limited knowledge. I have spent hours on this website trying to learn, but I cannot find this little question discussed. I am thinking of purchasing an intermediate Yamaha alto sax, however, the model/serial number/made in usa are engraved using a series of dots rather than a solid line. Most/all others I have seen use a solid line for this information. Does the use of dots suggest anything I should know before purchasing? Everything else about this instrument looks like normal Yamaha to me. Thanks for any help! I really enjoy this website.