A distinctly rarer variety of series designation, where the series is written only by letter (here PC), without being preceded by the Roman numeral "I". According to the latest edition of Czeslaw Miłczak's catalog, only 14 series are known from this variety, while the variety with the only one is as many as 66 series.
A diagonal, not strong, vertical fracture of the bill on the left side. Natural, presentation very nice.
