Can some help clarify the difference between a Post Mold & a Hinge Mold? I know the Post Mold had a circular ring & 2 base seams & the Hinge Mold usually had a base seam going straight across the base. This is a Hinge Mold that confuses me: http://www.sha.org/bottle/hostetterbase.jpg.Can someone help me understand the difference & help clear up this issue? Thanks for any advice!