), also known as an interrogation point, question point, query, or eroteme, is a punctuation mark that replaces the period at the end of an interrogative sentence. It can also be used mid-sentence to mark a merely interrogative phrase, where it functions similarly to a comma, such as in the single sentence "Where shall we go? and what shall we do?", but this usage is increasingly rare. The question mark is not used for indirect questions. The question mark character is also often used in place of missing or unknown data. Lynne Truss attributes an early form of the question mark to Alcuin of York. Truss describes the punctus interrogativus of the late 700s as "a lightning flash, striking from right to left", a mark looking like this. The punctuation system of Aelius Donatus, current through the Early Middle Ages, used only simple dots at various heights. This early question mark was a decoration of one of these dots, with the "lightning flash" perhaps meant to denote intonation, and perhaps associated with early musical notation like neumes. The symbol is also sometimes thought to originate from the Latin quaestiō (that is, qvaestio), meaning "question", which was abbreviated during the Middle Ages to Qo. The uppercase Q was written above the lowercase o, and this mark was transformed into the modern symbol. The name "question mark" was coined in the late 1800s by Lee Coleman. 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 1600s. 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 these are very rarely seen. Rhetorical questions in some (informal) situations can use a bracketed question mark, eg. "Oh, really(?)", for example in 888 subtitles. The question mark can also be used as a "meta" sign to signal uncertainty regarding what precedes. It is usually put between brackets (?). The uncertainty may concern either a superficial (such as unsure spelling) or a deeper truth, (real meaning) level. A question mark is used in English medical notes to suggest a possible diagnosis. It facilitates the recording of a doctor’s impressions regarding a patient’s symptoms and signs. For example, for a patient presenting with left lower abdominal pain, a differential diagnosis might include ?Diverticulitis (read as 'Query Diverticulitis').