D: Encyclopedia - D

D

The letter D is the fourth letter of the Latin alphabet. Its name in English is dee.

D - History

The Semitic letter Dâlet probably developed from the logogram for a fish or a door. In Semitic, Ancient Greek (Modern Greek /ð/) and Latin the letter was pronounced /d/, in the Etruscan alphabet the letter was superfluous but still maintained (see letter B). Greek letter: Δ (capital) or δ (small) (Delta).

The minuscule (lower-case) form of D, consisting of a loop and a tall vertical stroke, developed by gradual variations on the majuscule (capital) form. In handwriting it was common to start the arc to the left of the vertical stroke, resulting in a serif at the top of the arc. This serif was extended while the rest of the letter was reduced, resulting in an angled stroke and loop. The angled stroke then developed into a vertical stroke.

D - Usage

The letter D generally takes the voiced alveolar plosive value, IPA /d/ in most languages that use the Roman alphabet, including English. In Welsh d when doubled (dd) has the value /ð/, like English th in this.

Digraphs of D are rare in English, although other languages use DH or DD for a voiced dental fricative (some Celtic languages) or an aspirated voiced dental plosive (some Indo-Aryan languages), or use affricates DZ, DV, or DZH.

In Cantonese, the sound /d/ means a little bit, from the ancient use of the character 的 (in the phrase "兀的") in Chinese written language. Since 的 is no longer used in this way, Hong Kong residents invented a new character 啲 (which is not supported in many Chinese systems), or simply write D instead.

D - Alternative representations

Delta represents the letter D in the NATO phonetic alphabet, except in airports, to avoid confusion with Delta Air Lines, in which case it is Dixie.

In international Morse code the letter D is DahDitDit: - · ·

In Braille the letter D is represented as ⠙ (in Unicode), the dot pattern,

XX
.X
..

D - Computing

In Unicode the capital D is codepoint U+0044 and the lowercase d is U+0064.

The ASCII code for capital D is 68 and for lowercase d is 100; or in binary 01000100 and 01100100, correspondingly.

The EBCDIC code for capital D is 196 and for lowercase d is 132.

The numeric character references in HTML and XML are "D" and "d" for upper and lower case respectively.

D - Meanings for D

• In the atmosphere of Earth, the D layer is part of the ionosphere.
• In biochemistry, D is the symbol for aspartic acid.
• In British currency, d is an abbreviation (from the Latin denarius) for the pre-decimalization penny, worth 1/240th of a pound.
• In calendars, D is often an abbreviation for the month December.
• In chemistry, D is the symbol of deuterium, an isotope of hydrogen.
• D is a security division ("Minimal Protection") in the TCSEC.

• d is the symbol for the total differential operator (partial differentials use ∂).
• D is often used as a digit meaning thirteen in hexadecimal and other positional numeral systems with a radix of 14 or greater.

• d is the recommended symbol for: thickness, diameter, relative density (mechanics), lattice plane spacing (solid state physics), and degeneracy of vibrational mode (molecular spectroscopy).
• D is the recommended symbol for: diffusion coefficient (molecular physics), and Debye-Waller factor (solid state physics).
• D is the recommended symbol for electric displacement (electricity and magnetism).

See also

Category: Latin letters

Adapted from the Wikipedia article "D", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki