typography Typography is the art and technique of Typesetting, arranging type to make written language legibility, legible, readability, readable and beauty, appealing when displayed. The arrangement of type involves selecting typefaces, Point (typogra ...

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

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 computers. The numerical values that make up a c ...

. 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 ( ), an acronym for American Standard Code for Information Interchange, is a character encoding standard for representing a particular set of 95 (English language focused) printable character, printable and 33 control character, control c ...

code supports six different diacritics. These are:

grave accent The grave accent () ( or ) is a diacritical mark used to varying degrees in French, Dutch, Portuguese, Italian, Catalan and many other Western European languages as well as for a few unusual uses in English. It is also used in other ...

, tilde,

acute accent The acute accent (), , is a diacritic used in many modern written languages with alphabets based on the Latin alphabet, Latin, Cyrillic script, Cyrillic, and Greek alphabet, Greek scripts. For the most commonly encountered uses of the accen ...

(approximated by the

apostrophe The apostrophe (, ) is a punctuation mark, and sometimes a diacritical mark, in languages that use the Latin alphabet and some other alphabets. In English, the apostrophe is used for two basic purposes: * The marking of the omission of one o ...

), diaeresis (double quote),

cedilla A cedilla ( ; from Spanish language, Spanish ', "small ''ceda''", i.e. small "z"), or cedille (from French , ), is a hook or tail () added under certain letters (as a diacritic, diacritical mark) to indicate that their pronunciation is modif ...

(comma), and circumflex accent. 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 Unicode or ''The Unicode Standard'' or TUS is a character encoding standard maintained by the Unicode Consortium designed to support the use of text in all of the world's writing systems that can be digitized. Version 16.0 defines 154,998 Char ...

(especially

UTF-8 UTF-8 is a character encoding standard used for electronic communication. Defined by the Unicode Standard, the name is derived from ''Unicode Transformation Format 8-bit''. Almost every webpage is transmitted as UTF-8. UTF-8 supports all 1,112,0 ...

, which supports a much larger number of characters in different

writing system A writing system comprises a set of symbols, called a ''script'', as well as the rules by which the script represents a particular language. The earliest writing appeared during the late 4th millennium BC. Throughout history, each independen ...

s), this technique is of little use today. However,

combining character In digital typography, combining characters are Character (computing), characters that are intended to modify other characters. The most common combining characters in the Latin script are the combining diacritic, diacritical marks (including c ...

s 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 ''diacrit ...

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

Many

font In metal typesetting, a font is a particular size, weight and style of a ''typeface'', defined as the set of fonts that share an overall design. For instance, the typeface Bauer Bodoni (shown in the figure) includes fonts " Roman" (or "regul ...

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 Machine, mechanical or electromechanical machine for typing characters. Typically, a typewriter has an array of Button (control), keys, and each one causes a different single character to be produced on paper by striking an i ...

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. Overstriking with an offset was also used to created " Blackboard bold" style characters used in mathematics. 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, for example the functions and may be used to reverse the elements of an array. The WordPerfect word processor includes overstrike functionality. Collabora Online, LibreOffice and

Microsoft Word Microsoft Word is a word processor program, word processing program developed by Microsoft. It was first released on October 25, 1983, under the name Multi-Tool Word for Xenix systems. Subsequent versions were later written for several other platf ...

do not; however Collabora Online and LibreOffice allow the use of the characters X and / (forward slash) to overstrike, using the

strikethrough Strikethrough, or strikeout, is a typographical presentation of words with a horizontal line through their center, resulting in , sometimes an X or a forward slash is typed over the top instead of using a horizontal line. Strike-through was u ...

function. No known keyboard arrangement includes a function key that allows any two characters to be superimposed.

References

{{typography-stub Typography