It is used to describe the advancer's top honor card holdings in the overcaller's suit.
Either way, advancer's natural raise to the two-level denies possession of a top honor in that suit.
Showing the top honor may allow the overcaller with a serrated holding to lead the suit safely; while denying the top honor (and thereby suggesting strength elsewhere) encourages the overcaller to lead a different suit.
Subsequent to creating the Rosenkranz double and redouble, Rosenkranz announced in a letter published in the ACBL's Bridge Bulletin[citation needed][2] that he had adopted a proposal by Eddie Wold to switch the meaning of the two sequences, so that the advancer's immediate raise now showed the Ace, King or Queen honor, while the double (and redouble) denied it – a treatment known as "Reverse Rosenkranz".
The reasoning for the reverse treatment is that a better hand for the bid suit (by virtue of the additional honor strength) should raise the level of the auction to make things difficult for the opponents.