The modern numerical digit 0 is usually written as a circle, an ellipse or a rounded square or rectangle.

Glyphs

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In most modern typefaces, the height of the 0 character is the same as the other digits. However, in typefaces with text figures, the character is often shorter (x-height).

 
A comparison of the letter O and the number 0

Traditionally, many print typefaces made the capital letter O more rounded than the narrower, elliptical digit 0.[1] Typewriters originally made no distinction in shape between O and 0; some models did not even have a separate key for the digit 0. The distinction came into prominence on modern character displays.[1]

The digit 0 with a dot in the centre seems to have originated as an option on IBM 3270 displays. Its appearance has continued with Taligent's command line typeface Andalé Mono. One variation used a short vertical bar instead of the dot. This could be confused with the Greek letter Theta on a badly focused display, but in practice there was no confusion because theta was not (then) a displayable character and very little used anyway.

An alternative, the slashed zero (looking similar to the letter O except for the slash), was primarily used in hand-written coding sheets before transcription to punched cards or tape, and is also used in old-style ASCII graphic sets descended from the default typewheel on the Teletype Model 33 ASR. This form is similar to the symbol  , or "∅" (Unicode character U+2205), representing the empty set, as well as to the letter Ø used in several Scandinavian languages. Some Burroughs/Unisys equipment displays a digit 0 with a reversed slash.

The opposing convention that has the letter O with a slash and the digit 0 without was advocated by SHARE, a prominent IBM user group,[1] and recommended by IBM for writing FORTRAN programs,[2] and by a few other early mainframe makers; this is even more problematic for Scandinavians because it means two of their letters collide. Others advocated the opposite convention,[1] including IBM for writing Algol programs.[2] Another convention used on some early line printers left digit 0 unornamented but added a tail or hook to the capital O so that it resembled an inverted Q (like U+213A ) or cursive capital letter-O ( ).[1]

Some fonts designed for use with computers made one of the capital-O–digit-0 pair more rounded and the other more angular (closer to a rectangle). The TI-99/4A computer has a more angular capital O and a more rounded digit 0, whereas others made the choice the other way around.

 
German license plate with slit zeros

The typeface used on most European vehicle registration plates distinguishes the two symbols partially in this manner (having a more rectangular or wider shape for the capital O than the digit 0), but in several countries a further distinction is made by slitting open the digit 0 on the upper right side (as in German plates using the fälschungserschwerende Schrift, "forgery-impeding typeface").

Sometimes the digit 0 is used either exclusively, or not at all, to avoid confusion altogether. For example, confirmation numbers[3] used by Southwest Airlines use only the capital letters O and I instead of the digits 0 and 1, while Canadian postal codes use only the digits 1 and 0 and never the capital letters O and I, although letters and numbers always alternate.

Other

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On the seven-segment displays of calculators, watches, and household appliances, 0 is usually written with six line segments, though on some historical calculator models it was written with four line segments.

The international maritime signal flag has five plus signs in an X arrangement.

Zero symbols in Unicode

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  • U+0030 0 DIGIT ZERO
  • U+0660 ٠ ARABIC-INDIC DIGIT ZERO
  • U+06DF ۟ ARABIC SMALL HIGH ROUNDED ZERO
  • U+06E0 ۠ ARABIC SMALL HIGH UPRIGHT RECTANGULAR ZERO
  • U+06F0 ۰ EXTENDED ARABIC-INDIC DIGIT ZERO
  • U+07C0 ߀ NKO DIGIT ZERO
  • U+0966 DEVANAGARI DIGIT ZERO
  • U+09E6 BENGALI DIGIT ZERO
  • U+0A66 GURMUKHI DIGIT ZERO
  • U+0AE6 GUJARATI DIGIT ZERO
  • U+0B66 ORIYA DIGIT ZERO
  • U+0BE6 TAMIL DIGIT ZERO
  • U+0C66 TELUGU DIGIT ZERO
  • U+0C78 TELUGU FRACTION DIGIT ZERO FOR ODD POWERS OF FOUR
  • U+0CE6 KANNADA DIGIT ZERO
  • U+0D66 MALAYALAM DIGIT ZERO
  • U+0DE6 SINHALA LITH DIGIT ZERO
  • U+0E50 THAI DIGIT ZERO
  • U+0ED0 LAO DIGIT ZERO
  • U+0F20 TIBETAN DIGIT ZERO
  • U+0F33 TIBETAN DIGIT HALF ZERO
  • U+1040 MYANMAR DIGIT ZERO
  • U+1090 MYANMAR SHAN DIGIT ZERO
  • U+17E0 KHMER DIGIT ZERO
  • U+1810 MONGOLIAN DIGIT ZERO
  • U+1946 LIMBU DIGIT ZERO
  • U+19D0 NEW TAI LUE DIGIT ZERO
  • U+1A80 TAI THAM HORA DIGIT ZERO
  • U+1A90 TAI THAM THAM DIGIT ZERO
  • U+1B50 BALINESE DIGIT ZERO
  • U+1BB0 SUNDANESE DIGIT ZERO
  • U+1C40 LEPCHA DIGIT ZERO
  • U+1C50 OL CHIKI DIGIT ZERO
  • U+2070 SUPERSCRIPT ZERO
  • U+2080 SUBSCRIPT ZERO
  • U+2189 VULGAR FRACTION ZERO THIRDS
  • U+24EA CIRCLED DIGIT ZERO
  • U+24FF NEGATIVE CIRCLED DIGIT ZERO
  • U+3007 IDEOGRAPHIC NUMBER ZERO
  • U+3358 IDEOGRAPHIC TELEGRAPH SYMBOL FOR HOUR ZERO
  • U+A620 VAI DIGIT ZERO
  • U+A8D0 SAURASHTRA DIGIT ZERO
  • U+A8E0 COMBINING DEVANAGARI DIGIT ZERO
  • U+A900 KAYAH LI DIGIT ZERO
  • U+A9D0 JAVANESE DIGIT ZERO
  • U+A9F0 MYANMAR TAI LAING DIGIT ZERO
  • U+AA50 CHAM DIGIT ZERO
  • U+ABF0 MEETEI MAYEK DIGIT ZERO
  • U+FF10 FULLWIDTH DIGIT ZERO
  • U+1018A 𐆊 GREEK ZERO SIGN
  • U+104A0 𐒠 OSMANYA DIGIT ZERO
  • U+10D30 𐴰 HANIFI ROHINGYA DIGIT ZERO
  • U+11066 𑁦 BRAHMI DIGIT ZERO
  • U+110F0 𑃰 SORA SOMPENG DIGIT ZERO
  • U+11136 𑄶 CHAKMA DIGIT ZERO
  • U+111D0 𑇐 SHARADA DIGIT ZERO
  • U+112F0 𑋰 KHUDAWADI DIGIT ZERO
  • U+11366 𑍦 COMBINING GRANTHA DIGIT ZERO
  • U+11450 𑑐 NEWA DIGIT ZERO
  • U+114D0 𑓐 TIRHUTA DIGIT ZERO
  • U+11650 𑙐 MODI DIGIT ZERO
  • U+116C0 𑛀 TAKRI DIGIT ZERO
  • U+11730 𑜰 AHOM DIGIT ZERO
  • U+118E0 𑣠 WARANG CITI DIGIT ZERO
  • U+11950 𑥐 DIVES AKURU DIGIT ZERO
  • U+11C50 𑱐 BHAIKSUKI DIGIT ZERO
  • U+11D50 𑵐 MASARAM GONDI DIGIT ZERO
  • U+11DA0 𑶠 GUNJALA GONDI DIGIT ZERO
  • U+16A60 𖩠 MRO DIGIT ZERO
  • U+16B50 𖭐 PAHAWH HMONG DIGIT ZERO
  • U+16E80 𖺀 MEDEFAIDRIN DIGIT ZERO
  • U+1D2E0 𝋠 MAYAN NUMERAL ZERO
  • U+1D7CE 𝟎 MATHEMATICAL BOLD DIGIT ZERO
  • U+1D7D8 𝟘 MATHEMATICAL DOUBLE-STRUCK DIGIT ZERO
  • U+1D7E2 𝟢 MATHEMATICAL SANS-SERIF DIGIT ZERO
  • U+1D7EC 𝟬 MATHEMATICAL SANS-SERIF BOLD DIGIT ZERO
  • U+1D7F6 𝟶 MATHEMATICAL MONOSPACE DIGIT ZERO
  • U+1E140 𞅀 NYIAKENG PUACHUE HMONG DIGIT ZERO
  • U+1E2F0 𞋰 WANCHO DIGIT ZERO
  • U+1E950 𞥐 ADLAM DIGIT ZERO
  • U+1F100 🄀 DIGIT ZERO FULL STOP
  • U+1F101 🄁 DIGIT ZERO COMMA
  • U+1F10B 🄋 DINGBAT CIRCLED SANS-SERIF DIGIT ZERO
  • U+1F10C 🄌 DINGBAT NEGATIVE CIRCLED SANS-SERIF DIGIT ZERO
  • U+1F10D 🄍 CIRCLED ZERO WITH SLASH
  • U+1FBF0 🯰 SEGMENTED DIGIT ZERO
  • U+E0030 TAG DIGIT ZERO

See also

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References

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  1. ^ a b c d e Bemer, Robert William (August 1967). "Towards standards for handwritten zero and oh: much ado about nothing (and a letter), or a partial dossier on distinguishing between handwritten zero and oh". Communications of the ACM. 10 (8): 513–518. doi:10.1145/363534.363563. S2CID 294510.
  2. ^ a b Einarsson, Bo; Shokin, Yurij (2007-05-24). "Fortran 90 for the Fortran 77 Programmer". Appendix 7: "The historical development of Fortran. Archived from the original on 2017-02-28.
  3. ^ "Check in for your Flight Reservation".