Here is an example of the "G" mold variation. Note the wire groove is very clean ("H" mold has a glob of glass under the "M" in EC&M) and there is a very pronounced Mold line around the base. This line seems to vary in its location from 1/8" off the base to much higher. It should also be noted that if you measure from the top down to the mold line on the skirt you will find that is the documented measurements of the typical insulator highth. I hope that I have this all correct for the basics on this anomoly or extension of the skirt.