Since that post I have found the answer to the exclamatory question mark--it's called an Interrobang. Research shows that this mark was invented by American Martin K. Speckter in 1962. Speckter was head of an ad agency and believed ads would look better if copywriters showed surprised rhetorical questions with a single mark. He proposed the concept of a single punctuation mark in an article in the magazine TYPEtalks.
Speckter sought possible names for the new character from readers. Submissions included rhet, exclarotive, and exclamaquest, but he settled on interrobang. He chose the name to reference the punctuation marks that inspired it: interrogatio is Latin for "a rhethorical question" or "cross examination"; bang is printers' slang for the exclamation point. Possible graphic representations for the new mark were also sent in response to the article.
In 1966, Richard Isbell of American Type Founders issued the Americana typeface and included the interrobang as one of the characters. In 1968, an interrobang key was available on some Remington typewrites. During the 1970s, it was possible to buy replacement interrobang keycaps and typefaces for some Smith-Corona typewriters. The interrobang was popular for much of the 1960s, with the word interrobang appearing in some dictionaries and the mark itself being featured in magazine and newspaper articles.
Unfortunately, the interrobang failed to amount to much more than a fad. It has not become a standard punctuation mark. And yet, although most fonts do not include the interrobang, it has not disappeared: Microsoft provides several versions of the interrobang character as part of the Wingdings 2 character set (on the right bracket and tilde keys) available with Microsoft Office. It was also accepted into Unicode and is present in several fonts, including Lucida Sans, Unicode, Arial Unicode MS , and Calibri, the default font in the Office 2007 suite.
Bottom line: as with fadish words and phrases that become popularized through grassroots use and eventually make their way into dictionaries, I believe popular use of the interrobang will eventually force the powers that be in all matters punctuation (whoever that is) to finally accept it as a legitimate addition to our language. I, for one, intend to begin using it in informal writing. However, as a professional editor, I cannot use it or condone its use in formal writing until it has been properly recognized.
I hope you'll join me in promoting the use of the interrobang, because in my opinion, we're definitely missing this mark. One Down, // One To Go!
Your comments are welcomed and encouraged in response to this post.