More trivia: ASCII characters were designed to support overstrike (using BS) to generate more characters. For example, á (á) can be written as a BS '.

More trivia: ASCII characters were designed to support overstrike (using BS) to generate more characters. For example, á (á) can be written as a BS '. Acute, grave, and circumflex accents, and umlauts, can be written this way on lower-case letters. ñ is n BS ~. Cedille (ç) is c BS comma. Underline is character BS underscore; strikethrough is similar, using dash or tilde. Bold is character BS same_character. Many Compose key sequences are based on this. So ASCII, in a way, may well be the first -or one of the first- variable-length codeset. Note that overstriking upper-case letters to add diacritical marks does not work for ASCII (see more below). Also, overstriking was how one typed diacritical marks back in the days of mechanical typewriters. Spanish used to (and may still? I forget) permit upper-case letters to not carry diacritical marks precisely because it was difficult or costly to get typewriters and printers to print such letters. Adding diacritical marks to upper-case letters requires fonts designed for that, and clearly an overstrike sequence cannot work unless the typewriter/printer holds printing the character until it knows whether the next character is BS.