# Review of Content Standard

**Letter symbols to be used in electrical technology**

# IEC 60027 September, 2005 {#iec-60027-september-2005 .unnumbered}

1.  This review is intended to assess the potential utility of content
    standards for use and potentially for inclusion in an ISO
    11179-based metadata registry. The review is directed primarily
    toward the utility of the standard itself, rather than to matching
    the standard with specific agency programs. The review covers issues
    such as the subject area, currency, quality, authority, and
    acceptance of the standards. These are factors that need to be taken
    into account no matter what the programmatic application of the
    standard may be.

## 1. Summary

**IEC 60027** (formerly IEC 27) is the [International Electrotechnical
Commission](http://en.wikipedia.org/wiki/International_Electrotechnical_Commission)\'s
standard on *Letter symbols to be used in electrical technology*. It
consists of several parts:

-   IEC 60027-1: General

-   IEC 60027-2: Telecommunications and electronics

-   IEC 60027-3: Logarithmic and related quantities, and their units

-   IEC 60027-4: Symbols for quantities to be used for rotating
    electrical machines

A closely related international standard on
[quantities](http://en.wikipedia.org/wiki/Physical_quantity) and
[units](http://en.wikipedia.org/wiki/Physical_unit) is [ISO
31](http://en.wikipedia.org/wiki/ISO_31).

## Binary prefixes

A 1999 addendum to IEC 60027-2 on [**binary
prefixes**](http://en.wikipedia.org/wiki/Binary_prefixes) has resulted
in some public interest in the standard and is still being widely
discussed in the computer community, as it attempts to finally settle
the confusion about whether a kilobit corresponds to 1000 bits or 1024
bits.

## 2. Identification of Standard {#identification-of-standard .unnumbered}

### 2.1. Title

Letter symbols to be used in electrical technology

### 2.2. Acronym

IEC 60027

### 2.3. Web page(s), Identifier, or Contact Information:

### 2.3.1 Web page(s)

[http://www.iec.ch](http://www.iec.ch/)

### 2.3.2 Identifier

IEC 60027

### 2.3.3 Contact Information

### Secretariat: Italy -- Carlo Angelo Borghi

### 2.4 Authority

**2.4.1 Creator**

The **International Electrotechnical Commission (IEC)** is an
international [standards
organization](http://en.wikipedia.org/wiki/Standards_organization)
dealing with electrical, electronic and related technologies. Some of
its standards are developed jointly with
[ISO](http://en.wikipedia.org/wiki/International_Organization_for_Standardization).

The IEC is made up of representatives of national standards bodies. The
IEC was founded in [1906](http://en.wikipedia.org/wiki/1906) and
currently has more than 60 participating countries. Originally located
in [London](http://en.wikipedia.org/wiki/London), the commission moved
to its current headquarters in
[Geneva](http://en.wikipedia.org/wiki/Geneva) in
[1948](http://en.wikipedia.org/wiki/1948).

The IEC was instrumental in developing and distributing standards for
units of measurement, particularly the
[gauss](http://en.wikipedia.org/wiki/Gauss),
[hertz](http://en.wikipedia.org/wiki/Hertz), and
[weber](http://en.wikipedia.org/wiki/Weber_(Wb)). They also first
proposed a system of standards, the [Giorgi
System](http://en.wikipedia.org/wiki/Giovanni_Giorgi), which ultimately
became the [SI](http://en.wikipedia.org/wiki/SI) units. In
[1938](http://en.wikipedia.org/wiki/1938), it published an international
translating vocabulary to unify electrical terminology. This effort
continues, and the **International Electrotechnical Vocabulary** remains
an important work in the electrical and electronic industries.

IEC standards have numbers in the range 60000-79999 and their titles
take a form such as *IEC 60417: Graphical Symbols for use on Equipment*.
The numbers of older IEC standards were converted in 1997 by adding
60000, for example IEC 27 became IEC 60027. Standards developed jointly
with the ISO use ISO numbering standards and are titled such as *ISO/IEC
7498-1:1994 Open Systems Interconnection: Basic Reference Model*. The
ISO/IEC Joint Technical Committee 1 (ISO/IEC JTC1) is described in more
detail under ISO.

The mission of the International Electrotechnical Commission (IEC) is to
promote and coordinate international standardization and related
matters, such as the assessment of conformity to standards, in the
fields of electricity, electronics and related technologies. It deals
with these questions in a general way and leaves certain specific fields
such as telecommunications and motor vehicles to specialized
organizations.

The IEC was founded in 1906 and its present membership comprises the
national electrotechnical committees (NCs) of more than 50 countries,
including all industrialized and a growing number of industrializing
countries.

For its technical work, the IEC relies on some 200 technical committees
(TCs) and subcommittees (SCs). These are either horizontal or
product-oriented. Some 10 000 experts are active in the numerous Working
Groups (WGs).

**Scope of IEC/TC25**

The title of TC25 is \"Quantities and units, and their letter symbols\".
This horizontal committee was established in June 1935. Its standards
are of a general nature and are used by other TCs of the IEC (both
horizontal and product-oriented), by other international organizations,
by scientists and by industry.

The above title of TC 25 is, by the way, not a very fortunate choice.
The selection of letter symbols is at present only secondary to much
more fundamental work. A more appropriate title would be *Fundamental
concepts of electrotechnology*.

The scope of IEC/TC 25 is to prepare international standards on
quantities and units to be used generally in electrical technology, and
to review the use of quantities and units in IEC standards. These
standards should, whenever possible, be based on the SI (International
System). Such standards may be related to definitions, names, letter
symbols and their use; to the relations in which these quantities and
units appear; and to the signs and symbols used with them.

**2.4.2. Acceptance as authoritative**

A broad and truly international consensus must be reached, because
otherwise the IEC member countries and the other international
organizations would not adopt the fundamental concepts developed by
IEC/TC25.

Out of more than 50 IEC member countries, 17 are P-members. These are:
China, Czech Republic, Denmark, France, Germany, Italy, Japan, Korea
(Rep. of), Poland, Romania, Russian Federation, Spain, Sweden,
Switzerland, USA, United Kingdom, Yugoslavia.

Requests for new concepts (including quantities and units) may be
submitted by *any* TC/SC or NC.

Committee drafts are prepared in TC 25 either by the project leader or a
Working Group (in which experts from the relevant TCs/SCs and other
organizations may participate if necessary).

NCs consult their experts of TC25 and of any other committee concerned
in parallel and submit their collated comments in a *single* document.

The resulting draft is circulated to *all* parties concerned (including
other international organizations).

### 2.5 Publisher

International Electrotechnical Commission (IEC)

### 2.6 Language(s)

English and German (translated by DIN)

###  3. Content description

### 3.1 Subject area of content and area of application

In December 1998 the International Electrotechnical Commission (IEC),
the leading international organization for worldwide standardization in
electrotechnology, approved as an IEC International Standard names and
symbols for prefixes for binary multiples for use in the fields of data
processing and data transmission. The prefixes are as follows:

+-----------------------------------------------------------------------+
| **Prefixes for binary multiples**                                     |
+-----------------------------------------------------------------------+
|   -----------                                                         |
| --- ----------- ------------- --------------------- ----------------- |
|   ** Factor                                                           |
|  **   **Name **   **Symbol **   **Origin**            **Derivation ** |
|                                                                       |
|    2^10^                                                              |
|      kibi        Ki            kilobinary:           kilo: (10^3^)^1^ |
|                                            (2^10^)^1^                 |
|                                                                       |
|    2^20^                                                              |
|      mebi        Mi            megabinary:           mega: (10^3^)^2^ |
|                                            (2^10^)^2 ^                |
|                                                                       |
|    2^30^                                                              |
|      gibi        Gi            gigabinary:           giga: (10^3^)^3^ |
|                                            (2^10^)^3^                 |
|                                                                       |
|    2^40^                                                              |
|      tebi        Ti            terabinary:           tera: (10^3^)^4^ |
|                                            (2^10^)^4^                 |
|                                                                       |
|    2^50^                                                              |
|      pebi        Pi            petabinary:           peta: (10^3^)^5^ |
|                                            (2^10^)^5^                 |
|                                                                       |
|    2^60^                                                              |
|       exbi        Ei            exabinary: (2^10^)^6^ exa: (10^3^)^6^ |
|   -----------                                                         |
| --- ----------- ------------- --------------------- ----------------- |
+-----------------------------------------------------------------------+
|                                                                       |
+-----------------------------------------------------------------------+
|   -------------------- ---------------------------------------------  |
|   **Examples and                                                      |
|   comparisons with SI                                                 |
|   prefixes**                                                          |
|                                                                       |
|   one **kibibit**       1 Kibit = 2^10^ bit = **1024 bit**            |
|                                                                       |
|   one **kilobit**       1 kbit = 10^3^ bit = **1000 bit**             |
|                                                                       |
|   one **mebibyte**      1 MiB = 2^20^ B = **1 048 576 B**             |
|                                                                       |
|   one **megabyte**      1 MB = 10^6^ B = **1 000 000 B**              |
|                                                                       |
|   one **gibibyte**      1 GiB = 2^30^ B = **1 073 741 824 B**         |
|                                                                       |
|   one **gigabyte**      1 GB = 10^9^ B = **1 000 000 000 B**          |
|   -------------------- ---------------------------------------------  |
+-----------------------------------------------------------------------+

It is suggested that in English, the first syllable of the name of the
binary-multiple prefix should be pronounced in the same way as the first
syllable of the name of the corresponding SI prefix, and that the second
syllable should be pronounced as \"bee.\"

It is important to recognize that the new prefixes for binary multiples
are not part of the International System of Units (SI), the modern
metric system. However, for ease of understanding and recall, they were
derived from the SI prefixes for positive powers of ten. As can be seen
from the above table, the name of each new prefix is derived from the
name of the corresponding SI prefix by retaining the first two letters
of the name of the SI prefix and adding the letters \"bi,\" which
recalls the word \"binary.\" Similarly, the symbol of each new prefix is
derived from the symbol of the corresponding SI prefix by adding the
letter \"i,\" which again recalls the word \"binary.\" (For consistency
with the other prefixes for binary multiples, the symbol Ki is used for
2^10^ rather than ki.)

These prefixes for binary multiples, which were developed by IEC
Technical Committee (TC) 25, Quantities and units, and their letter
symbols, with the strong support of the International Committee for
Weights and Measures (CIPM) and the Institute of Electrical and
Electronics Engineers (IEEE), were first adopted by the IEC as
*Amendment 2 to IEC International Standard IEC 60027-2: Letter symbols
to be used in electrical technology - Part 2: Telecommunications and
electronics*. The full content of *Amendment 2,* which has a publication
date of 1999-01, is reflected in the tables above and the suggestion
regarding pronunciation. Subsequently the contents of this Amendment
were incorporated in the second edition of IEC 60027-2, which has a
publication date of 2000-11 (the first edition was published in 1972).
The complete citation for this revised standard is IEC 60027-2, Second
edition, 2000-11, *Letter symbols to be used in electrical technology -
Part 2: Telecommunications and electronics.*

http://physics.nist.gov/cuu/Units/binary.html

### 3.2 Kind of content

Gives letter symbols for quantities and units used in electrical
technology, and rules for their use and combination. Also specifies
alphabets, subscripts, singularity functions, distributions and letter
styles

### 3.3 Audience(s)

The TC25 standards are of a general nature and are used by other TCs of
the IEC (both horizontal and product-oriented), by other international
organizations, by scientists and by industry.

A broad and truly international consensus must be reached, because
otherwise the IEC member countries and the other international
organizations would not adopt the fundamental concepts developed by
IEC/TC25.

### 3.4 Related Standards/3.5 Standards Dependencies {#related-standards3.5-standards-dependencies .unnumbered}

See the CMAP "Relationships of Standards and Guidance Documents for SI
Units"

### 

**3.6 Content Quality**

The introduction of the metric system during the French revolution and
the rapid development of the mathematical formulation of the physical
sciences led in the middle of the last century to the creation of a
coherent three-dimensional system of units. It was founded on the
mechanical base units centimetre (length), gram (mass), second (time)
and was apt to describe all mechanical, electric and magnetic phenomena.

This \"absolute\" CGS-system has been of tremendous importance for the
development of physics as an empirical science. There were, however,
difficulties due to the inconvenient size of some of the electrical
units and to the existence of the three varieties of the system
(electrostatic, electromagnetic and Gaussian). Further problems were
related to the physical understanding of the dimensions.

The Italian scientist and engineer *Giovanni* *Giorgi* discovered, by
the end of the last century, that the above points could be solved by
expanding the three-dimensional system to a four-dimensional one: a base
quantity of *electrical* nature had to be added (e.g. ohm, ampere or
coulomb).

He also showed that the CGS system could be combined with the three
mechanical units metre, kilogram and second, to constitute together with
the electrical unit one coherent four-dimensional system of units. This
concept was of fundamental importance, but it took many years to reach a
general consensus.

The *IEC* was able to provide the appropriate forum that was necessary
for these discussions to take place. As a result, the IEC Committee of
Action adopted in 1935 the principle of Giorgi\'s four fundamental
units; it confirmed in 1938 the units metre, kilogram, second, ampere
and decided to call this system the Giorgi System or MKSA System.

Giorgi\'s breakthrough opened the way for additional adaptations of this
system resulting from the needs of three other technical fields.

Thermodynamics: addition of *thermodynamic temperature*; unit Kelvin.\
Luminous radiation: addition of *luminous intensity*; unit candela.\
Chemistry: addition of *amount of substance*; unit mole.

This led finally to the general acceptance of the Système International
(SI). IEC publication 60027 is based on the SI.

 

### 4. Currency of Content {#currency-of-content .unnumbered}

### 4.1 Date

Parts published from 1995 to 2005.

### 4.2 Versions, Updates/4.3 Currency

### Editions range from Ed. 1 to Ed. 6.

**5. Acceptance**

Well accepted by the electrotechnical community.

### 

### 6. Content details/6.1 Size statistics (estimated)/6.2 Format / Schemas(s)/6.3 Media / Download/6.4 Licensing Issues/6.5 Documentation

From the ANSI Document Store, PDF downloads available:

http://webstore.ansi.org/ansidocstore/

  ------------- -------------------------------------------------------------------------------------------------------- ---------- -----------
  Document \#   Document Title                                                                                           Price      Member
                                                                                                                                    Discount
                                                                                                                                    Available

  IEC 60027-1   [Amendment No.                                                                                           \$20.00    Yes
  Amd.1 Ed. 6.0 1](http://webstore.ansi.org/ansidocstore/product.asp?sku=IEC+60027-1+Amd.1+Ed.+6.0+b%3A1997)                        
  b:1997                                                                                                                            

  IEC 60027-1   [Letter symbols to be used in electrical technology - Part 1: General (Corrected and reprinted           \$138.00   Yes
  Ed. 6.0       1995-03-31)](http://webstore.ansi.org/ansidocstore/product.asp?sku=IEC+60027-1+Ed.+6.0+b%3A1992)                    
  b:1992                                                                                                                            

  IEC 60027-2   [Letter symbols to be used in electrical technology - Part 2: Telecommunications and                     \$163.00   Yes
  Ed. 3.0       electronics](http://webstore.ansi.org/ansidocstore/product.asp?sku=IEC+60027-2+Ed.+3.0+b%3A2005)                    
  b:2005                                                                                                                            

  IEC 60027-3   [Letter symbols to be used in electrical technology - Part 3: Logarithmic and related quantities, and    \$43.00    Yes
  Ed. 3.0       their units](http://webstore.ansi.org/ansidocstore/product.asp?sku=IEC+60027-3+Ed.+3.0+b%3A2002)                    
  b:2002                                                                                                                            

  IEC 60027-4   [Letter symbols to be used in electrical technology. Part 4: Symbols for quantities to be used for       \$40.00    Yes
  Ed. 1.0       rotating electrical                                                                                                 
  b:1985        machines](http://webstore.ansi.org/ansidocstore/product.asp?sku=IEC+60027-4+Ed.+1.0+b%3A1985)                       

  IEC/PAS       [Letter symbols to be used in electrical technology - Control                                            \$37.00    Yes
  60027-6 Ed.   technology](http://webstore.ansi.org/ansidocstore/product.asp?sku=IEC%2FPAS+60027-6+Ed.+1.0+en%3A2004)              
  1.0 en:2004                                                                                                                       
  ------------- -------------------------------------------------------------------------------------------------------- ---------- -----------

  ---------------- ------------------------------------------------------
  Document#:       IEC 60027-1 Amd.1 Ed. 6.0 b:1997

  Title:           Amendment No. 1

  Abstract:        NONE

  Normative        No normative references available
  References:      

  File Size:       165 kB

  Price:           \$20.00
  ---------------- ------------------------------------------------------

  ---------------- ------------------------------------------------------
  Document#:       IEC 60027-1 Ed. 6.0 b:1992

  Title:           Letter symbols to be used in electrical technology -
                   Part 1: General (Corrected and reprinted 1995-03-31)

  Abstract:        \"Gives letter symbols for quantities and units used
                   in electrical technology, and rules for their use and
                   combination. Also specifies alphabets, subscripts,
                   singularity functions, distributions and letter
                   styles. \"

  Normative        No normative references available
  References:      

  File Size:       4.11 MB

  Price:           \$138.00
  ---------------- ------------------------------------------------------

  ---------------- ------------------------------------------------------
  Document#:       IEC 60027-2 Ed. 3.0 b:2005

  Title:           Letter symbols to be used in electrical technology -
                   Part 2: Telecommunications and electronics

  Abstract:        Defines rules for the use and writing of letter
                   symbols for telecommunications and electronics.

  Normative        No normative references available
  References:      

  File Size:       1.17 MB

  Price:           \$163.00
  ---------------- ------------------------------------------------------

  ------------- ---------------------------------------- --------- -----------
  Document \#   Document Title                           Price     Member
                                                                   Discount
                                                                   Available

  IEC 60027-3   Letter symbols to be used in electrical  \$43.00   Yes
  Ed. 3.0       technology - Part 3: Logarithmic and               
  b:2002        related quantities, and their units                
  ------------- ---------------------------------------- --------- -----------

  ------------- ---------------------------------------- --------- -----------
  Document \#   Document Title                           Price     Member
                                                                   Discount
                                                                   Available

  IEC 60027-4   Letter symbols to be used in electrical  \$40.00   Yes
  Ed. 1.0       technology. Part 4: Symbols for                    
  b:1985        quantities to be used for rotating                 
                electrical machines                                
  ------------- ---------------------------------------- --------- -----------

  ---------------- ------------------------------------------------------
  Document#:       IEC/PAS 60027-6 Ed. 1.0 en:2004

  Title:           Letter symbols to be used in electrical technology -
                   Control technology

  Abstract:        \"Applies to control technology. Gives names and
                   symbols for quantities, signals and functions and
                   their units. Replaces IEC 60027-2, section 11.\"

  Normative        No normative references available
  References:      

  File Size:       972 kB

  Price:           \$37.00
  ---------------- ------------------------------------------------------