A-Abundant, readily available, often in wholesale quantities.
C-Common, always available. Occasionally in quantity.
R1-Usually available without a long delay. Difficult to find in quantity.
R2-Scarce to rare, less seldom available.
R3-Rare. Difficult to find.
R4-Very rare. Demand outstrips supply, and specimens, when
available are often eagerly sought.
R5-Extremely rare and seldom available. Collector may have to
search for a few years to locate one.
R6-Of the highest rarity. Very difficult to obtain.
R7-Almost never available. Most collectors will not have a chance to acquire these pieces.
R8-Never been on the market. Almost impossible to obtain.
R*-Not available for collections.