Environmental Data Coding Specification

7 EDCS Units

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7.1 Introduction

7.1.1 Table of contents

See Table 7.1 for the table of contents for this clause.

7 EDCS Units	Table 7.1 -- Table of contents	Table 7.8 -- EDCS Unit Equivalence Class Dictionary Entries
7.1 Introduction	Table 7.2 -- EDCS Unit Dictionary Entry fields	Table 7.9 -- EDCS Unit Equivalence Class Dictionary
7.1.1 Table of contents	Table 7.3 -- EDCS Unit Dictionary Entries	Table 7.10 -- EDCS Unit Equivalence Class Dictionary Entries
7.1.2 Overview	Table 7.4 -- EUs whose label begins with A-L	Table 7.11 -- EQs whose label begins with A-I
7.2 EDCS Unit Dictionary	Table 7.5 -- EUs whose label begins with M-Z	Table 7.12 -- EQs whose label begins with J-N
7.3 EDCS Unit Scale Dictionary	Table 7.6 -- Unit Scale Dictionary for powers of 10	Table 7.13 -- EQs whose label begins with O-Z
7.4 EDCS Unit Equivalence Class Dictionary	Table 7.7 -- Unit Scale Dictionary for powers of 2¹⁰

This International Standard uses EDCS Units (EUs) to characterize the values of physical quantities and conforms to the International System of Units (SI) as defined in ISO 31:1994. The EDCS Units Dictionary is presented in tables with its EDCS Dictionary Entries grouped alphabetically by the first letter of the EUL.

This International Standard uses EDCS Unit Scales (ESs) to provide scaling information for use in conjunction with EUs. The EDCS Unit Scale Dictionary is presented in tables with its EDCS Dictionary Entries organized by the value of the multiplicative constant (scale factor).

This International Standard defines EDCS Unit Equivalence Classes (EQs), which are sets of units of measure that are equivalent in the sense that they characterize the same physical quantity. The EDCS Unit Equivalence Class Dictionary is presented in tables with its EDCS Dictionary Entries grouped alphabetically by the first letter of the EQL.

7.2 EDCS Unit Dictionary

This International Standard uses EUs to characterize the values of physical quantities and conforms to the International System of Units (SI) as defined in ISO 31. Where possible, units of measure used in this International Standard are taken from or derived from those defined in ISO 31. Each EU has a unique definition, and is designated by both a unique EUL and a unique EUC. EUs are further characterized by a symbol and by membership in a class of equivalent units called an EQ.

The EUs specified in this International Standard are listed in Table 7.3 and presented in Table 7.4 through Table 7.5. Units of measure whose use is deprecated are listed separately in Annex B. The contents of each field of an EDCS Units Dictionary Entry fields are listed in Table 7.2. Note that all references in the EDCS Unit Dictionary are Normative References, so the Reference type field is omitted in this EDCS Dictionary.

Table 7.2 -- EDCS Unit Dictionary Entry fields

Field	Contents
Label	The EUL (see 4.2.2 Labels).
Symbol	The symbol for the EU. If an EU has no symbol, "none" is entered in this field.
EQ label	The EQL (see 4.8 Unit Equivalence Classes).
Quantity / Definition	The quantity associated with the EU and a definition of the EU, including any value in terms of SI base units if the symbol is not already in terms of SI base units.
Code	The EUC (see 4.2.3 Codes).
References	The references for this EU (see 4.2.4 References). In almost all cases, this field contains references to the part of ISO 31 where this unit is defined or an explanation of its derivation from units defined in ISO 31.

In Table 7.4, Table 7.5 and in Table B.1 the notation "re" means "referenced to." For example, "dB (re 1 μPa)" means "decibels referenced to one (1) microPascal."

Table 7.3 -- EDCS Unit Dictionary Entries

Table 7.4 -- EUs whose label begins with A-L

Table 7.5 -- EUs whose label begins with M-Z

7.3 EDCS Unit Scale Dictionary

This International Standard uses ESs to provide scaling information for use in conjunction with EUs. Some units of measure for the same physical quantity can be converted one to the other by means of a linear equation. When the multiplicative constant (scale factor) in that linear equation is a certain power of ten or 2¹⁰ (and the additive constant is zero), this International Standard specifically treats them as ESs. Each ES has a unique definition, and is designated by both a unique ESL and a unique ESC.

The contents of each field of an EDCS Unit Scale Dictionary Entry are listed in Table 7.6. Note that all references in the EDCS Unit Scale Dictionary are Normative References, so the Reference type field is omitted in this EDCS Dictionary.

Table 7.6 -- EDCS Unit Scale Dictionary Entry fields

Field	Contents
Label	The ESL (see 4.2.2 Labels).
Symbol	The symbol for the ES. If an ES has no symbol, "none" is entered in this field.
Definition	The multiple or sub-multiple factor of the ES.
Code	The ESC (see 4.2.3 Codes).

The EDCS Unit Scale Dictionary is presented in Table 7.7 and Table 7.8 with its EDCS Dictionary Entries organized by the value of the multiplicative constant (scale factor). All entries in Table 7.7 are normatively referenced to ISO 31-0:1992, Table 4.

Table 7.7 -- Unit Scale Dictionary for powers of 10

Label	Symbol	Definition	Code
YOTTA	Y	10²⁴	1
ZETTA	Z	10²¹	2
EXA	E	10¹⁸	3
PETA	P	10¹⁵	4
TERA	T	10¹²	5
GIGA	G	10⁹	6
MEGA	M	10⁶	7
KILO	k	10³	8
HECTO	h	10²	9
DECA	da	10¹	10
UNI	1	10⁰	11
DECI	d	10^-1	12
CENTI	c	10^-2	13
MILLI	m	10^-3	14
MICRO	μ	10^-6	15
NANO	n	10^-9	16
PICO	p	10^-12	17
FEMTO	f	10^-15	18
ATTO	a	10^-18	19
ZEPTO	z	10^-21	20
YOCTO	y	10^-24	21

All entries in Table 7.8 are normatively referenced to IEC 60027-2:2000.

Table 7.8 -- Unit Scale Dictionary for powers of 2¹⁰

Label	Symbol	Definition	Code
KIBI	Ki	2¹⁰	22
MEBI	Mi	2²⁰	23
GIBI	Gi	2³⁰	24
TEBI	Ti	2⁴⁰	25
PEBI	Pi	2⁵⁰	26
EXBI	Ei	2⁶⁰	27

7.4 EDCS Unit Equivalence Class Dictionary

This International Standard defines EQs, which are sets of units of measure that are equivalent in the sense that they characterize the same physical quantity. Each EQ has a unique definition, and is designated by both a unique EQL and a unique EUC. The EDCS Unit Equivalence Class Dictionary is presented in tables with its EDCS Dictionary Entries grouped alphabetically by the first letter of the EQL.

The EQCs specified in this International Standard are presented in Tables 7.11 through 7.13. The contents of each field of an EDCS Unit Equivalence Class Dictionary Entry are listed in Table 7.9.

Table 7.9 -- EDCS Unit Equivalence Class Dictionary Entry fields

Field	Contents
Label	The EQL (see 4.2.2 Labels).
Definition	The definition of the quantity of which the members of this EQ are called "quantities of the same kind" [I310].
Equivalence class membership	The list of EULs that are members of the EQ.
Code	The EQC (see 4.2.3 Codes).

Table 7.10 -- EDCS Unit Equivalence Class Dictionary Entries

Table 7.11 -- EQs whose label begins with A-I

Table 7.12 -- EQs whose label begins with J-N

Table 7.13 -- EQs whose label begins with O-Z