Usage Notes: Metric Units IN OUR A P R I L ISSUE we started to use the capital " L " as
the symbol for the SI unit, the litre. In written text the symbol L will be used alone or in combination with a symbol for an SI prefix only when accompanied by a numeral that reflects a specific measured quantity—for example, 5.2 L; 100 mL; 5 d L . (Symbols for units of measurement may appear without numerals in tables and figures.) This use of the symbol L is based on a recent recommendation of the International Committee for Weights and Measures (CIPM) that the General Conference on Weights and Measures ( C G P M ) recognize the capital L as well as the lowercase 1 as the official SI symbols (1). The capital L had previously been endorsed by the the American Chemical Society (2), the U.S. National Bureau of Standards (3), and the Canadian Standards Association (4). It has also been accepted by journals published by the American Institute of Physics (5). In accord with the official recommendations for SI units issued by the C G P M (6), we are using the symbol s for second (time). We will also use d for day and min for minute, which are the symbols recommended by the C G P M (6) for use with the SI and endorsed by other scientific organizations (5, 7-9). These symbols are to be used only when accompanied by a numeral reflecting a specific measured quantity of time: " T h e dose was continued for 5 d." When used in a general statement, the unit is written out: " H e exercised for about 15 minutes." Guidelines for use of these and other symbols and abbreviations can be found in the Council of Biology Editors Style Manual (10).—The Editor References 1. U.S. M E T R I C ASSOCIATION: CIPM recommends **L" for litre. US Metric Assoc Newslett 13(4):7, 1978 2. AMERICAN CHEMICAL SOCIETY: Handbook for Authors. Washington, D.C., American Chemical Society Publications, 1978 3. NATIONAL BUREAU OF STANDARDS: The metric system of measurement: interpretation and modification of the International System of Units for the United States. Fed Regist 41(239):54018-54019, 1976 4. CANADIAN STANDARDS ASSOCIATION: Metric Practice Guide, CANZ234.1-76. Rexdale, Ontario, Canadian Standards Association, 1976 5. AMERICAN INSTITUTE OF PHYSICS: Style Manual. New York, American Institute of Physics, 1978 6. C O N F E R E N C E G E N E R A L E DES P O I D S E T M E S U R E S [General Conference
on Weights and Measures]: The International System of Units (SI). Washington, D.C., National Bureau of Standards (special publication 330), 1974 7. A M E R I C A N SOCIETY FOR T E S T I N G A N D M A T E R I A L S : Standard for Met-
ric Practice, ANSI/ASTM E 380-76h. Philadelphia, American Society for Testing and Materials, 1976 8. BIOSCIENCES INFORMATION SERVICE: BIOSIS Guide to Abstracts. Philadelphia, Biological Abstracts, Inc., 1977 9. LOWE DA: A Guide to International Recommendations on Names and Symbols for Quantities and on Units of Measurement. Geneva, World Health Organization, 1975 10. CBE STYLE M A N U A L COMMITTEE: Council of Biology Editors Style Manual. A Guide for Authors, Editors, and Publishers in the Biological Sciences, 4th ed. Council of Biology Editors, 1978
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the symbol for the SI unit, the litre. In written text the symbol L will be used alone or in combination with a symbol for an SI prefix only when accompanied by a numeral that reflects a specific measured quantity—for example, 5.2 L; 100 mL; 5 d L . (Symbols for units of measurement may appear without numerals in tables and figures.) This use of the symbol L is based on a recent recommendation of the International Committee for Weights and Measures (CIPM) that the General Conference on Weights and Measures ( C G P M ) recognize the capital L as well as the lowercase 1 as the official SI symbols (1). The capital L had previously been endorsed by the the American Chemical Society (2), the U.S. National Bureau of Standards (3), and the Canadian Standards Association (4). It has also been accepted by journals published by the American Institute of Physics (5). In accord with the official recommendations for SI units issued by the C G P M (6), we are using the symbol s for second (time). We will also use d for day and min for minute, which are the symbols recommended by the C G P M (6) for use with the SI and endorsed by other scientific organizations (5, 7-9). These symbols are to be used only when accompanied by a numeral reflecting a specific measured quantity of time: " T h e dose was continued for 5 d." When used in a general statement, the unit is written out: " H e exercised for about 15 minutes." Guidelines for use of these and other symbols and abbreviations can be found in the Council of Biology Editors Style Manual (10).—The Editor References 1. U.S. M E T R I C ASSOCIATION: CIPM recommends **L" for litre. US Metric Assoc Newslett 13(4):7, 1978 2. AMERICAN CHEMICAL SOCIETY: Handbook for Authors. Washington, D.C., American Chemical Society Publications, 1978 3. NATIONAL BUREAU OF STANDARDS: The metric system of measurement: interpretation and modification of the International System of Units for the United States. Fed Regist 41(239):54018-54019, 1976 4. CANADIAN STANDARDS ASSOCIATION: Metric Practice Guide, CANZ234.1-76. Rexdale, Ontario, Canadian Standards Association, 1976 5. AMERICAN INSTITUTE OF PHYSICS: Style Manual. New York, American Institute of Physics, 1978 6. C O N F E R E N C E G E N E R A L E DES P O I D S E T M E S U R E S [General Conference
on Weights and Measures]: The International System of Units (SI). Washington, D.C., National Bureau of Standards (special publication 330), 1974 7. A M E R I C A N SOCIETY FOR T E S T I N G A N D M A T E R I A L S : Standard for Met-
ric Practice, ANSI/ASTM E 380-76h. Philadelphia, American Society for Testing and Materials, 1976 8. BIOSCIENCES INFORMATION SERVICE: BIOSIS Guide to Abstracts. Philadelphia, Biological Abstracts, Inc., 1977 9. LOWE DA: A Guide to International Recommendations on Names and Symbols for Quantities and on Units of Measurement. Geneva, World Health Organization, 1975 10. CBE STYLE M A N U A L COMMITTEE: Council of Biology Editors Style Manual. A Guide for Authors, Editors, and Publishers in the Biological Sciences, 4th ed. Council of Biology Editors, 1978
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