1st dot is black for mica caps with 6 dots. 1st dot is silver for paper cpas with 6 dots. My diagrams show these with 3 dots each with an arrow on the top three. Seems to depend on whether the caps are RMA or JAN RMA: Radio manufactures association JAN: Joint Army-Navy. info taken from back of an r-388 manual. Bill, VE3JHU