Environmental Data Coding Specification

7 EDCS units

7.1 Introduction

7.1.1 Table of contents

7 EDCS units	7.1.2 Overview	7.4 EDCS Unit Equivalence Class Dictionary
7.1 Introduction	7.2 EDCS Unit Dictionary
7.1.1 Table of contents	7.3 EDCS Unit Scale Dictionary

Table 7.2 — Table of tables

Table 7.1 — Table of contents	Table 7.6 — EUs whose label begins with M-Z	Table 7.11 — EDCS Unit Equivalence Class Dictionary entry fields
Table 7.2 — Table of tables	Table 7.7 — EUs not in the scope of SI	Table 7.12 — EDCS Unit Equivalence Class Dictionary tables
Table 7.3 — EDCS Unit Dictionary entry fields	Table 7.8 — EDCS Unit Scale Dictionary entry fields	Table 7.13 — EQs whose label begins with A-I
Table 7.4 — EDCS Unit Dictionary tables	Table 7.9 — Unit Scale Dictionary for powers of 10	Table 7.14 — EQs whose label begins with J-N
Table 7.5 — EUs whose label begins with A-L	Table 7.10 — Unit Scale Dictionary for powers of 2¹⁰	Table 7.15 — EQs whose label begins with O-Z

This International Standard specifies EDCS units that characterize the values of physical quantities and may conform to the International System of Units as specified in ISO 31. Within the EDCS Unit Dictionary, each EU has one or more quantities and is denoted by both a unique EUL and a unique EUC. Each quantity has a unique concept definition.

The EDCS Unit Dictionary is presented in four tables: two tables of EUs derived from the International System of Units (ordered alphabetically by EUL), one table of EUs outside the scope of the International System of Units, and one table of deprecated EUs. Within each table, the EUs are ordered alphabetically by the EUL.

This International Standard specifies EDCS unit scales that provide scaling information for use in conjunction with EUs. Within the EDCS Unit Scale Dictionary, each ES has a unique concept definition and is denoted by both a unique ESL and a unique ESC.

The EDCS Unit Scale Dictionary is presented in two tables with the ESs ordered by the value of the multiplicative constant (scale factor) in each table.

This International Standard specifies EDCS unit equivalence classes that are sets of units of measure that characterize the same physical quantity. Within the EDCS Unit Equivalence Class Dictionary, each EQ has a unique concept definition and is denoted by both a unique EQL and a unique EQC.

The EDCS Unit Equivalence Class Dictionary is presented in three tables ordered alphabetically by the EQL. Within each table, the EQs are ordered alphabetically by the EQL.

The concepts of EU, EQ, and ES are related as follows. Each instance of an EA whose EDCS attribute value type is REAL has:

an EU (see 7.2) that belongs to the EQ (see 7.4) of that EA, and
an ES (see 7.3) that specifies a power of ten or 2¹⁰ that is a multiplicative scale factor for the value of the instance of that EA.

7.2 EDCS Unit Dictionary

The EDCS Unit Dictionary is presented in Table 7.5 through Table 7.7 and in Table A.6. The specification of each field of an EDCS Unit Dictionary entry is presented in Table 7.3. Units of measure whose use is deprecated are presented separately in Table A.6. The reference type for each entry in the EDCS Unit Dictionary is PR except for those entries presented in Table 7.7. Therefore the reference type field is omitted in Table 7.5, Table 7.6, and Table A.6.

An EU may have more than one quantity. When this is the case, the quantity, concept definition, reference type, reference, and supplemental references fields are repeated.

Table 7.3 — EDCS Unit Dictionary entry fields

Field	Specification	Location
Label	The EUL (see 4.3.2).	Clause 7 and Annex A
Symbol	The symbol for this EU. If the EU has no symbol, "none" is entered in this field.	Clause 7 and Annex A
Quantity	A quantity associated with this EU; additional synonymous quantities may be included parenthetically.	Clause 7 and Annex A
Concept definition	The concept definition of the quantity, including an expression for the quantity in terms of SI base units if the value of the symbol field is not in terms of SI base units (see 4.3.1).	Clause 7 and Annex A
EQ label	The EQL (see 4.10).	Clause 7 and Annex A
Code	The EUC (see 4.3.3).	Clause 7 and Annex A
Reference type	The EDCS reference type of this reference (see 4.3.4.2).	Clause 7
Reference	The reference for this quantity (see 4.3.4.3). For EUs within the scope of SI, either this field contains a reference to the part of ISO 31 where this quantity is defined or this field contains an explanation of its derivation from quantities defined in ISO 31.	Clause 7 and Annex A
Supplemental references	The supplemental references for this quantity (see 4.3.4.4).	Clause 7 and Annex A

In Table 7.5 through Table 7.7 and in Table A.6, the notation "re" means "referenced to." For example: "dB (re 1 μPa)" means "decibels referenced to one (1) microPascal."

Table 7.4 — EDCS Unit Dictionary tables

Table 7.5 — EUs whose label begins with A-L

Table 7.6 — EUs whose label begins with M-Z

Table 7.7 — EUs not in the scope of SI

Table A.6 — Deprecated EUs

7.3 EDCS Unit Scale Dictionary

The EDCS Unit Scale Dictionary is presented in Table 7.9 and Table 7.10 with its EDCS dictionary entries ordered by the value of the multiplicative constant (scale factor). The specification of each field of an EDCS Unit Scale Dictionary entry is presented in Table 7.8. The reference type for each entry in the EDCS Unit Scale Dictionary is PR, therefore the reference type, reference, and supplemental references fields are omitted.

Table 7.8 — EDCS Unit Scale Dictionary entry fields

Field	Specification	Location
Label	The ESL (see 4.3.2).	Clause 7
Symbol	The symbol for this ES.	Clause 7
Concept definition	Either the multiple or the submultiple scale factor of the ES.	Clause 7
Code	The ESC (see 4.3.3).	Clause 7

The reference type for each entry in Table 7.9 is PR. The reference for each entry in Table 7.9 is ISO 31-0:1992, Table 4.

Table 7.9 — Unit Scale Dictionary for powers of 10

Label	Symbol	Concept 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

The reference type for each entry in Table 7.10 is PR. The reference for each entry in Table 7.10 is IEC 60027-2.

Table 7.10 — Unit Scale Dictionary for powers of 2¹⁰

Label	Symbol	Concept 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

The EDCS Unit Equivalence Class Dictionary is presented in Tables 7.13 through 7.15. The specification of each field of an EDCS Unit Equivalence Class Dictionary entry is presented in Table 7.11. No entry in the EDCS Unit Equivalence Dictionary has a reference type, reference, or supplemental references, therefore these fields are omitted.

Table 7.11 — EDCS Unit Equivalence Class Dictionary entry fields

Field	Specification	Location
Label	The EQL (see 4.3.2).	Clause 7
Concept definition	The concept definition of the quantity of which the members of this EQ are called "quantities of the same kind" (see ISO 31-0).	Clause 7
Equivalence class membership	The list of EULs of the EUs that are members of the EQ. The EULs of EUs that are part of the International System of Units are presented in bold. The EULs of EUs that are deprecated EDCS units (see Table A.6) are presented in italics. The remaining EUs are those based on units of measure specified in the International System of Units.	Clause 7
Code	The EQC (see 4.3.3).	Clause 7

Table 7.12 — EDCS Unit Equivalence Class Dictionary tables

Table 7.13 — EQs whose label begins with A-I

Table 7.14 — EQs whose label begins with J-N

Table 7.15 — EQs whose label begins with O-Z

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