When persons were going abroad or were to be absent for a long period, if they had not the time or inclination to take leave of their friends by making formal calls, they would send cards folded in this manner, or inscribed PPC, which stood for pour prendre congé (although many assumed the initials to stand for "presents parting compliments") or PDA, which stood for pour dire adieu. Other card inscriptions included: PC--pour condoler; PF--pour féliciter; and PP--pour présenter. In each case, these inscriptions would be made in ink, in uppercase letters, in the lower left-hand corner. If a card was enclosed within an envelope, it usually indicated that communication between the two parties was at an end. The three exceptions to this rule were: a) when they were sent to a newly married couple; b) when they were in reply to a wedding invitation and sent by someone absent from their usual home; c) when they were PPC or PDA cards. In 1857, the Duke of Parma starte the custom of leaving cartes de visite with his portrait for the albums of friends. Visiting cards were sometimes nicknamed paste boards. So, to "shoot a PB" was to leave one's card.
In amtters of grave importance, style, not sincerity, is the vital thing. Oscar Wilde (1854-1900)