Question mark

The question mark, ?, was a piece of punctuation used by many languages on Earth to denote an interrogative.

As Fashion for The Doctor
During some of his incarnations, the Doctor appeared to adopt the question mark as something of a personal motif. The Fourth, Fifth, and Sixth Doctors displayed question marks on the collars of their shirts. (DW: The Leisure Hive, Castrovalva, The Twin Dilemma, Time and the Rani) The Seventh Doctor wore a jumper covered with the symbol, carried an umbrella with a question-mark-shaped handle, carried a business card with a stylized question mark, and when asked to sign his name, did so with a question mark. (DW: Remembrance of the Daleks)


 * It was unclear whether the Doctor regarded the symbol as a question mark or as an unknown Gallifreyan symbol. Neither he nor any companion ever explicitly referred to the motif as a question mark.