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to this occurs when the kilogram is one of the units. For
example:
V/m, not mV/mm; MJ/kg, not kJ/g
4.3. -Compound prefixes
Compound prefixes, formed by the juxtaposition of two
or more SI prefixes, are not to be used. For example:
1 nm not lmpm; 1 pF not 1 p p F
If vaIues are required outside the range covered by the
prefixes, they should be expressed using powers of ten
applied to the base unit.
4.4. -Powers of units
An exponent attached to a symbol containing a prefix
indicates that the multiple or sub-multiple of the unit (the
unit with its prefix) is raised to the power expressed by the
exponent. For example:
5 . S t y l e and usage
5.1.-Rules for writing unit symbols
5.1.1 Unit symbols should be printed in Roman
(upright) type regardless of the type style used in the
surrounding text.
5.1.2 Unit symbols are unaltered in the plural.
5.1.3 Unit symbols are not followed by a period
except when used at the end of a sentence.
5.1.4 Letter unfi symbols are written in lower case
(cd) unless the unit name has been derived from a proper
name, in which case the first letter of the symbol is
capitalized (W, Pa). Prefix and unit symbols retain their
prescribed form regardless of the surrounding typography.
5.1.5 In the complete expression for a quantity, a
space should be left between the numerical value and the
unit symbol. For example, write 35 mm not 35mm, and
2.37 Im, not 2.371m. When the quantity is used in an
adjectival sense, a hyphen is often used, for example,
35-mm film.
Exception: No space is left between the numerical value
and the symbols for degree, minute and second of plane
angle, and degree Celsius.
5.1.6 No space is used between the prefix and unit
symbols.
5.1.7 Symbols, not abbreviations, should be used for
units. For example, use ','A", not "amp", for ampere.
5.2.-Rules for writing unit names
5.2.1 Spelled-out unit names are treated as common
nouns in English. Thus, the first letter of a unit name is not
capitalized except at the beginning of a sentence or in
capitalized material such as a title, even though the unit
name may be derived from a proper name and therefore be
represented as a symbol by a capital letter (see 5.1.4). For
example, normally write "newton" not "Newton" even
though the symbol is N.
5.2.2 Plurals are used when required by the rules of
grammar and are normally formed regularly, for example,
henries for the plural of henry. The following irregular
plurals are recommended:
Singular Plural
lux lux
hertz hertz
siemens siemens
1. A cotnpound u n i ~is a derived u n ie~x pressed in (ernis of (wo or niore uniis.
(ha( is. no( expressed wilh a single special name.
Attachment B
Annex 5 - Units of Measurement to be used in Air
and Ground Operations
5.2.3 No space or hyphen is used between the prefix
and the unit name.
5.3.-Units formed by multiplication and division
5.3.1 With unit names:
Product, use a space (preferred) or hyphen:
newton metre or newton-metre
in the case of the watt hour the space may be omitted,
thus:
watthour
Quotient, use the word per and not a solidus:
metre per second not metrelsecond.
Powers, use the modifier squared or cubed placed after
the unit name:
metre per second squared
In the case of area or volume, a modifier may be placed
before the unit name:
square millimetre, cubic metre.
This exception also applies to derived units using area or
volume:
watt per square metre.
Note. -To avoid ambiguity in complicated expressions,
symbols are prefirred to words.
5.3.2 With unit symbols:
Product may be indicated in either of the following ways:
Nm or N . m for newton metre.
Note.- When using for a prefuc a symbol which coincides
with the symbol for the unit, special care should be taken to avoid
confusion. The unit newton metre for torque should be written,
,for aample, Nm or N . m to avoid confusion with mN, the
millinewton.
An exception to this practice is made for computer printouts,
automatic typewriter work, etc., where the dot half
high is not possible, and a dot on the line may be used.
Quotient, use one of the following forms:
mls or m . s-I or
S
In no case should more than one solidus be used in the same
expression unless parentheses are inserted to avoid
ambiguity. For example, write:
J/(mol . K) or J . mol-I . K-I or (J1mol)IK
but not J/mol/K.
5.3.3 Symbols and unit names should not be mixed
in the same expression. Write:
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附件5--空中和地面运行中所使用的计量单位(28)
