Overstrike

typography Typography is the art and technique of arranging type to make written language legible, readable and appealing when displayed. The arrangement of type involves selecting typefaces, point sizes, line lengths, line-spacing ( leading), ...

, overstrike is a method of printing characters that are missing from the

printer Printer may refer to: Technology * Printer (publishing), a person or a company * Printer (computing), a hardware device * Optical printer for motion picture films People * Nariman Printer (fl. c. 1940), Indian journalist and activist * James ...

character set Character encoding is the process of assigning numbers to graphical characters, especially the written characters of human language, allowing them to be stored, transmitted, and transformed using digital computers. The numerical values tha ...

. The character is created by placing one character on another one — for example, overstriking "L" with "-" results in printing a "Ł" ( L with stroke) character. The

ASCII ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because ...

code supports six different

diacritics A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph added to a letter or to a basic glyph. The term derives from the Ancient Greek (, "distinguishing"), from (, "to distinguish"). The word ''diacriti ...

. These are: grave accent,

tilde The tilde () or , is a grapheme with several uses. The name of the character came into English from Spanish, which in turn came from the Latin '' titulus'', meaning "title" or "superscription". Its primary use is as a diacritic (accent) i ...

, acute accent (approximated by the apostrophe), diaeresis (double quote), cedilla (comma), and

circumflex accent The circumflex () is a diacritic in the Latin and Greek scripts that is also used in the written forms of many languages and in various romanization and transcription schemes. It received its English name from la, circumflexus "bent around"a ...

. Each is typed by typing the preceding character, then backspace, and then the 'related character', which is `, ~, ', ", , or ^, respectively for the above-mentioned accents. With the wide adoption of Unicode (especially UTF-8, which supports a much larger number of characters in different writing systems), this technique is of little use today. However, combining characters such as

diacritic A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph added to a letter or to a basic glyph. The term derives from the Ancient Greek (, "distinguishing"), from (, "to distinguish"). The word ''diacriti ...

s are still used to depict characters which cannot be shown otherwise. Bold text using overstrike

Many font renderers in computer programs invent missing bold characters by overstriking the normal character with itself, slightly horizontally offset. The horizontal offset is essential since, unlike a

typewriter A typewriter is a mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of keys, and each one causes a different single character to be produced on paper by striking an inked ribbon selectivel ...

where repeating a letter in exactly the same space will make it darker, most modern printers will not darken repeated "strikes" to the same space. Actual bold fonts are designed with some features thicker and others the same size as a regular font, so the use of this "fake bold" is considered undesirable from a typographic point of view. The character set for the APL programming language includes several characters that were printed by overstriking other characters on printing terminals such as the

IBM 2741 The IBM 2741 is a printing computer terminal that was introduced in 1965. Compared to the teletypewriter machines that were commonly used as printing terminals at the time, the 2741 offers 50% higher speed, much higher quality printing, quieter op ...

, for example the functions ⌽ and ⊖ may be used to reverse the elements of an array. WordPerfect word processing program included an overstrike functionality. Word and LibreOffice/OpenOffice do not. No known keyboard arrangement includes a function key that allows any two characters to be superimposed. Typography {{typography-stub