Question mark
The rhetorical question mark or percontation point was invented by Henry Denham in the 1580s and was used at the end of a rhetorical question; however, its use died out in the 17th century. It was later revived in modern-day society by Matt DiRoberto. It was the reverse of an ordinary question mark, so that instead of the main opening pointing back into the sentence, it opened away from it. This character can be represented using the reversed question mark (⸮) found in Unicode as U+2E2E. The percontation point is analogous to the irony mark, but those are even more rarely seen.
Irony punctuation
Irony punctuation is any proposed form of notation used to denote irony or sarcasm in text. Written English lacks a standard way to mark irony, and several forms of punctuation have been proposed. Among the oldest and most frequently attested is the percontation point proposed by English printer Henry Denham in the 1580s, and the irony mark, used by Marcellin Jobard and French poet Alcanter de Brahm during the 19th century. Both marks take the form of a reversed question mark, "⸮".