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10. Signs and Symbols

10.1. Th e increased use of signs and symbols and their importance in technical and scientifi c work have emphasized the necessity of standardization on a national basis and of the consistent use of the standard forms.

10.2. Certain symbols are standardized—number symbols (the digits, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9); letter symbols (the letters of the alphabet, a, b, c, d, etc.); and graphic symbols (the mathematical signs +, −, ±, ×, ÷).

10.3. Th e signs +, −, ±, ×, and ÷, etc., are closed against accompanying fi gures and symbols. When the × is used to indicate “crossed with” (in plant or animal breeding) or magnifi cation, it will be separated from the accompanying words by a space.

i–vii+1–288 pages Early June × Bright (crossed with)Th e equation A+B × 4 (magnifi cation)Th e result is 4×4 miles ÷ gallons20,000±5,000

Symbols with fi gures10.4. In technical publications the degree mark is used in lieu of the word

degree following a fi gure denoting measurement.

10.5. Following a fi gure, the spelled form is preferred. Th e percent sym-bol is used in areas where space will not allow the word percent to be used. In that period the price rose 12, 15, and 19 percent.not In that period the price rose 12 percent, 15 percent, and 19 percent.

10.6. Any symbol set close up to fi gures, such as the degree mark, num-ber mark, dollar mark, or cent mark, is used before or aft er each fi gure in a group or series.

$5 to $8 price range but5'–7' long, not 5–7' long § 12 (thin space)3¢ to 5¢ (no spaces) ¶ 1951 (thin space)±2 to ±7; 2°±1° from 15 to 25 percent#61 to #64 45 to 65 °F not 45° to 65° F

260 Chapter 10

Letter symbols10.7. Letter symbols are set in italic (see rule 10.8) or in roman (see rule

9.56) without periods and are capitalized only if so shown in copy, since the capitalized form may have an entirely diff erent meaning.

Equations10.8. In mathematical equations, use italic for all letter symbols—capitals,

lowercase, small capitals, and superiors and inferiors (exponents and subscripts); use roman for fi gures, including superiors and inferiors.

10.9. If an equation or a mathematical expression needs to be divided, break before +, −, =, etc. However, the equal sign is to clear on the left of other beginning mathematical signs.

10.10. A short equation in text should not be broken at the end of a line. Space out the line so that the equation will begin on the next line; or better, center the equation on a line by itself.

10.11. An equation too long for one line is set fl ush left , the second half of the equation is set fl ush right, and the two parts are balanced as nearly as possible.

10.12. Two or more equations in a series are aligned on the equal signs and centered on the longest equation in the group.

10.13. Connecting words of explanation, such as hence, therefore, and simi-larly, are set fl ush left either on the same line with the equation or on a separate line.

10.14. Parentheses, braces, brackets, integral signs, and summation signs should be of the same height as the mathematical expressions they include.

10.15. Inferiors precede superiors if they appear together; but if either in-ferior or superior is too long, the two are aligned on the left .

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Signs and Symbols 261

Chemical symbols10.16. Th e names and symbols listed below are approved by the

International Union of Pure and Applied Chemistry. Th ey are set in roman without periods.

Actinium ............................ Ac 89Aluminum ......................... Al 13Americium ........................ Am 95Antimony .......................... Sb 51Argon .................................. Ar 18Arsenic .............................. As 33Astatine .............................. At 85Barium ............................... Ba 56Berkelium .......................... Bk 97Beryllium ........................... Be 4Bismuth .............................. Bi 83Bohrium ............................. Bh 107Boron .................................. B 5Bromine ............................. Br 35Cadmium ........................... Cd 48Calcium .............................. Ca 20Californium ...................... Cf 98Carbon ............................... C 6Cerium ............................... Ce 58Cesium ............................... Cs 55Chlorine ............................. Cl 17Chromium ......................... Cr 24Cobalt ................................. Co 27Copper ................................ Cu 29Curium ............................... Cm 96Darmstadtium .................. Ds 110Dubnium ........................... Db 105Dysprosium ....................... Dy 66Einsteinium ....................... Es 99Erbium ............................... Er 68Europium ........................... Eu 63Fermium ............................ Fm 100Fluorine .............................. F 9Francium ........................... Fr 87Gadolinium ....................... Gd 64Gallium .............................. Ga 31Germanium....................... Ge 32Gold .................................... Au 79Hafnium ............................ Hf 72Hassium ............................. Hs 108Helium ............................... He 2Holmium ........................... Ho 67Hydrogen ........................... H 1Indium ............................... In 49Iodine ................................. I 53Iridium ............................... Ir 77Iron ..................................... Fe 26Krypton .............................. Kr 36Lanthanum ........................ La 57Lawrencium ...................... Lr 103Lead ..................................... Pb 82Lithium .............................. Li 3Lutetium ............................ Lu 71Magnesium........................ Mg 12Manganese ........................ Mn 25Meitnerium ....................... Mt 109

Mendelevium .................... Md 101Mercury ............................. Hg 80Molybdenum .................... Mo 42Neodymium ...................... Nd 60Neon ................................... Ne 10Neptunium ........................ Np 93Nickel .................................. Ni 28Niobium ............................. Nb 41Nitrogen ............................. N 7Nobelium ........................... No 102Osmium ............................. Os 76Oxygen ............................... O 8Palladium .......................... Pd 46Phosphorus........................ P 15Platinum ............................ Pt 78Plutonium .......................... Pu 94Polonium ........................... Po 84Potassium .......................... K 19Praseodymium ................. Pr 59Promethium ...................... Pm 61Protactinium ..................... Pa 91Radium ............................... Ra 88Radon ................................. Rn 86Rhenium ............................ Re 75Rhodium ............................ Rh 45Roentgenium .................... Rg 111Rubidium ........................... Rb 37Ruthenium ........................ Ru 44Rutherfordium ................. Rf 104Samarium .......................... Sm 62Scandium ........................... Sc 21Seaborgium ....................... Sg 106Selenium ............................ Se 34Silicon ................................. Si 14Silver ................................... Ag 47Sodium ............................... Na 11Strontium........................... Sr 38Sulfur .................................. S 16Tantalum ........................... Ta 73Technetium ....................... Tc 43Tellurium ........................... Te 52Terbium .............................. Tb 65Th allium ............................ Tl 81Th orium ............................. Th 90Th ulium ............................. Tm 69Tin ....................................... Sn 50Titanium ............................ Ti 22Tungsten ............................ W 74Uranium ............................ U 92Vanadium .......................... V 23Xenon ................................. Xe 54Ytterbium ........................... Yb 70Yttrium ............................... Y 39Zinc ..................................... Zn 30Zirconium ......................... Zr 40

Element Symbol Symbol AtomicNo.

AtomicNo. Element

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262 Chapter 10

Standardized symbols10.17. Symbols duly standardized by any national scientifi c, profes-

sional, or technical group are accepted as preferred forms within the fi eld of the group. Th e issuing offi ce desiring or requiring the use of such standardized symbols should see that copy is prepared accordingly.

Signs and symbols10.18. Th e following list contains some signs and symbols frequently used

in printing. Th e forms and style of many symbols vary with the method of reproduction employed. It is important that editors and writers clearly identify signs and symbols when they appear within a manuscript.

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Signs and Symbols 263

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264 Chapter 10

1 Standard letter symbols used by the Geological Survey on geologic maps. Capital letter indicates the system and one or more lowercased letters designate the formation and member where used.

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