ลำดับชั้นที่กำหนดลักษณะของพฤติกรรมกระแสแม่เหล็กบริเวณจุดดับบนดวงอาทิตย์ กำหนดโดยหอดูดาว Mount Wilson ในแคลิฟอร์เนีย
alpha: A unipolar sunspot group.
beta: A sunspot group having both positive and negative magnetic polarities (bipolar), with a simple and distinct division between the polarities.
gamma: A complex active region in which the positive and negative polarities are so irregularly distributed as to prevent classification as a bipolar group.
beta-gamma: A sunspot group that is bipolar but which is sufficiently complex that no single, continuous line can be drawn between spots of opposite polarities.
delta: A qualifier to magnetic classes(see below) indicating that umbrae separated by less than 2 degrees within one penumbra have opposite polarity.
beta-delta: A sunspot group of general beta magnetic classification but containing one (or more) delta spot(s).
beta-gamma-delta: A sunspot group of beta-gamma magnetic classification but containing one (or more) delta spot(s).
gamma-delta: A sunspot group of gamma magnetic classification but containing one (or more) delta spot(s).