OverStrike control character

abraham gross abrahamgross at disroot.org
Tue Jun 9 17:51:34 CDT 2020

What do yall think about adding an OverStrike control character?

Theres historical precedence of having such a control character. The famous Symbolics Space Cadet keyboard had such a key, and many typewriters relied on the its functionality (e.g. in order to make a ⟨!⟩ you had to type ⟨'<BS>.⟩ in most typewriters up until the mid 1900s)

The programming language APL also heavily relied on the overstrike control character, so many systems in the 80s had the character including Lisp machines.

Here's a quote from the Lisp Machine manual: “OVER STRIKE: Moves the cursor back so that you can superpose (overlay) two characters, should you really want to. The key called BS will do the same thing on the old keyboards.” (The BackSpace key in Lisp Machines worked like they do in typewriters where it just went back a character. The Rub Out key actually deleted the last character)

Unicode/ASCII currently has at ASCII 8 the character "BS" thats supposed to go back a character without deleting it, and "DEL" at ASCII 127 that does delete the character. But nowadays BS just deletes the previous character. In fact, it's prohibited in ISO/IEC 8859 for BS to not delete the previous character. Wikipedia says: “[The cancel control character is] A control character ("CCH", "Cancel Character", U+0094, or ESC T) used to erase the previous character. This character was created as an unambiguous alternative to the much more common backspace character ("BS", U+0008), which has a now mostly obsolete alternative function of causing the following character to be superimposed on the preceding one.”

Modern Usage: Since no modern systems have such a control character, you won't find it being used anywhere, but I can guarantee that it will receive wide adoption, especially in east asia, because the kaomoji community will have a field-day with it.  
People looking to add diacritics that aren't encoded as a combining character yet will also now have the option to do ⟨<letter><OverStrike><funky diacritic>⟩ like ⟨g<OS>꒙⟩ would come out looking like a "g" with a sideways "Z" on top.

Another use of the OverStrike key will be combining shapes in new creative ways for custom orthographies or for custom symbols that can be sent over plain text without the need for special fonts. (since unicode will never encode anyone's random conscript/symbols, this would be a great way for people to get this usage with only the addition of a single character)

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