A bipolar group with penumbra on spots of both polarities, usually on spots at the both ends of an elongatede group. The lenght does not exceed 10 degrees of heliographic lognitude. E A bipolar group with penumbra on spots of both polarities and the lenght between 10 and 15 heliographic lognitude. F A bipolar group with penumbra on spots of both polarities and wit a lenght exceeding 15 heliographic degrees. H A unipolar group with penumbra.
Attendent spots are less than three heliographic degrees from the penumbra of the main spot.
The principal spots are nearly become compact class D when the penumbra exceed 5 degrees in lognitudes extent. The width of the gray area bordering spots must exceed three arc seconds in order to classify as penumbra. It is usually incomplete, irrular outline, as narrow as three arc seconds, brighter intensity than normal penumbra, and has a mottled, or granular, fine structure. Rudimentary penumbra presents the transition between photosphere granulation and filamentary penumbra. The umbrae form a compact cluster near the center of the penumbra.