I read somewhere that Class A and Classa 15 bobbins are the same. Does anyone know if this is true? I have an embroidery machine on layaway and want to get a head start on supplies. When I went to order some thread on a website, the thread comes with matching prewound bobbins but all they had for choices were L and A. My dealer said that the model I am buying calls for Class 15. Thanks for any help you can give me.