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British Amateur Television Club

BATC logo Date & Time


The BATC and the ISO 8601 Date and Time Standard:

A Common Date/Time Standard for Amateur Radio.

Information Compiled by: Ian Galpin, G1SMD for the BATC Web Pages.

Around the world, Dates and Times have always caused many problems. This is especially so in an International activity such as Amateur Radio where communication both across language barriers and national conventions may introduce some doubt as to what is meant.

We generally write times using 'hh:mm:ss' or 'hh:mm'. Imagine the chaos if some countries used 'ss:mm:hh', others 'mm:ss:hh'. What would a time like '10:05:08' then mean to different people?

We now use the 24-hour time format rather than the old 12-hour am/pm system.

The use of Local Time can also cause confusion, especially as some countries change their Legal Time by one hour during their Summer months. Different countries often also change on different dates. We avoid these problems by using the UTC (Universal Time, Co-ordinated) Time Zone, world-wide. UTC was formerly known as GMT (Greenwich Mean Time). In this way users only need to know their own local offset to UTC not anyone else's.

All of these methods are defined in an International Standard called ISO 8601.

For dates, every country seems to do something different. The date '04/01/80' means '4th January' in Britain, but 'April 1st' in America. This can lead to problems in computer programs, on QSL cards, on Web Pages, in email, and in newsletters. In a few years time we will also have dates like '02/05/03' and '04/09/05' to contend with.

ISO 8601 has a solution to these problems. The date is written using the full four digits for the year, with the order Year-Month-Day, and hyphen separators. A leading Zero is used for '01' to '09'.

However, I note that the ISO standard only refers to wholly numeric dates. Whilst I realise that a date written as '4th January 1980', here in Britain, is clear enough in itself; over in America that same date would be written as 'January 4th, 1980'. This again shows a difference in style, one that merely reflects the old '04/01/80' (dd/mm/yy) and '01/04/80' (mm/dd/yy) short-hand date formats.

Astronomers have used the Year-Month-Day Date Format for over 200 years; but happily interchange the month as 2-digits, a 3-letter abbreviation, or written out in full. In this way the following Dates are all equivalent, easily interchangeable, and are consistent in format:

    1980-01-04          (or  '19800104'  in program data storage)

    1980-Jan-04         (or  '1980 Jan 04'  without the hyphens).

    1980-January-04     (or  '1980 January 04'  without the hyphens).

They are all based on the Year-Month-Day order with a 4-digit year.

The Time is written in any of the following ways:

    23:44:59            (or  '234459'  in program data storage).

    23:44               (or  '2344'  without the colon separators).

The ISO format is clear, unambiguous and cannot be confused with any other existing format. For a Time expressed in UTC, the ISO standard defines that the Time should be followed by the letter 'Z'. Amateur Radio operators may be happier to use the term 'UTC' or just 'UT', in the same way that astronomers do.

The ISO 8601 standard has already been adopted as ANSI X3.30-1985(R1991) in America. In Europe, the ISO standard has been implemented as a 'EuroNorm' Standard. Under the CEN regulations every member state is required to adopt this EN 28601:1992 standard (all of Western Europe and Scandinavia, and most of Eastern Europe). In Japan see the JIS X 0301-1992 standard. Many other countries have signed up to the ISO 8601 standard. A list has been compiled at:

ISO 8601 has been in use in Scandinavia, parts of East Europe, and most of Asia for many years, and by astronomers for over 200 years. They realised, long ago, the advantage of working to a common standard, world-wide.

In Britain '1980-01-04' has been translated to '4th January 1980' in the past.
In America '1980-01-04' has been translated to 'January 4th, 1980' in the past.

Astronomers happily interchange dates like '1980-01-04', '1980-Jan-04', '1980-January-04', '1980 January 04', '1980 Jan 04' and '1980 January 4th' at will. These formats are all based on the Year-Month-Day order and are highly recommended for use within Amateur Radio.

Many people are adopting these formats in fixing the Year 2000 Problem with computer systems. In recent times, IBM has promoted and used the ISO standard in its Year 2000 Book. IBM use the '1997-Oct-20' date format all the way through recent editions of their Year 2000 Book (IBM Publication GC28-1251-xx). This book is available for viewing or download at:

The 'full' ISO format solves the Year 2000 Problem as well as the UK / US date format ambiguity. Both DOS and Windows already have provision for the Year-Month-Day method built in, as have a number of Amateur Radio programs. The instructions for DOS and Windows can be found at:

A new 'Filer' Template for the Acorn RiscPC machine can be found in the ZIP file located at: This information was compiled by James Miller, G3RUH.

The Amateur Radio Proposal, written by Ian Galpin, G1SMD, in 1996, recommends adoption of the ISO format for all facets of the Amateur Radio hobby: computer programs, log books, QSL cards, email and packet messages, Web Pages, band reports, newsletters, and so on. The proposal can be viewed at: This copy of the document also includes a short introduction by John Morris GM4ANB, who is another supporter and user of this format.

The Amateur Radio Proposal Document is also available as a plain text version at:

The German magazine DUBUS has adopted the new format, as has the Meteor Scatter software by OH5IY, and the new EME programs by VK3UM. G3SEK is rewriting all his software to cope with the Year 2000 and to adopt the ISO format. G0RUR is using it in his software in 1998. G3RUH has used it for very many years. The ITU are using the ISO format on their Web Page at: and in some of their documents. The 'Four Metres News' newsletter (edited by G3NKS) has also adopted the new method. The BATC has now adopted this format on their Web Pages, and in their CQ-TV magazine. G3TZO (CQ-TV Satellite TV News Column) and G8IQU (CQ-TV Magazine Editor) are already keen supporters of this proposal.

I note that the US military have adopted the '1997-Jul-15' format according to a recent edition of the US computer magazine 'Byte' (1997-July, Page 89); and this format is now also being used on the new European Passports.

This is the only Internationally agreed format, and I recommend its use to all Radio Amateurs. Use a 4-digit Year and the Year-Month-Day order. We all understand the time '22:44:59'. There should be no problems with the date '1998-02-10', whereas '10/02/98' will always have a different meaning across the two sides of the Atlantic. ISO 8601 replaces 'dd/mm/yy' and 'mm/dd/yy' with 'yyyy-mm-dd'.

Note that Dates are always written before Times in the standard. This method really comes into its own when looking down a column of Dates and Times (such as in a Log Book, in a contest entry, band-listings in a magazine, or in satellite pass times output from satellite tracking software).

The new format may well be a bit of a 'culture shock', at first, to some people in the UK, but the use is growing and spreading. Many people are already quite happy to use it, now that they know all the built-in advantages that it brings. It is especially popular in Scandinavia, East Europe, and Asia. The 'dd/mm/yy' and 'mm/dd/yy' formats are just minor regional formats that are now outdated.

In a few years time, the date '01/01/01' will arrive. In America the next day will be '01/02/01'. In Britain, it will be '02/01/01'. In Japan it will be '01/01/02'. Under the ISO 8601 scheme, the day after '2001-01-01' is simply '2001-01-02'.

Similarly, the date '2001 February 03' is written as '2001-02-03' under the ISO 8601 format, but confusingly as '03/02/01' or '02/03/01' or '01/02/03' under the old national formats of various different countries.

Most of the world has signed up to ISO 8601 - all of West Europe, most of East Europe, America, Canada (where it has been known as the 'metric date' since 1972), Australia, New Zealand, South Africa, Israel, most of Asia (common place in Korea, China, Japan), and many others. It is the way forwards, even if the average 'Joe Ham' hasn't heard about it before.

The Amateur Radio Proposal Document was printed, in full, in the German VHF/UHF magazine DUBUS, in the 1997-Q1 issue (on Page 83 to 85). The new format has been adopted by DL8LAQ writing in the MS Reports, and Aurora News columns. DL5BCU uses the ISO 8601 format in the 'Es News' information; and OZ1IPU has recently started using it in the Microwave: 'World Firsts and DX Records' table of that magazine.

The Proposal Document is also available in HTML Format on Internet from a site run by GM4ANB located at: Copies of the proposal have already been circulated to all major committees of the RSGB, as well as to other organisations such as ARRL, IARU, AMSAT and so on.

The RSGB contest rules already call for entries to use the Year-Month-Day format on any computer generated logs (but only a 2-digit year is specified at present). The Year-Month-Day format is also specified in two recent standards defining Amateur Radio data storage formats. These are the ADIF standard written by WN4AZY and WF1B, and the REG1TEST format devised by OZ1FTU and OZ1FDJ.

More information on the Year 2000 and on ISO 8601 issues can be found at: This file also includes instructions for DOS and Windows to use the ISO 8601 format. There is also an extensive list of sources of further information from magazines and on Internet.

There are also articles printed in CQ-TV 180 (Page 9 to 11) and CQ-TV 181 (Page 75 to 77), published by the BATC. These can also be downloaded from this site ( The articles contain more background information on this proposal, and instructions for setting up various computers to use this format.

A short general description of the ISO 8601 Date Format can also be found at:

My own Web Page with more Year 2000 and ISO 8601 information is at:

Find out how IBM-compatible Computer Hardware is affected by the Year 2000 Problem at:

The instructions for setting up both DOS and Windows for the Year-Month-Day format can be found at:

The World Wide Web Consortium (the people that control technical standards on Internet) are considering the ISO 8601 date format for use in all future Internet working. Their document is at:

The following people are already supporters of this proposal, and users of the new format: G3RZV, G6CGQ, GM4ANB, DL4EBY, DL8LAQ, G3XWH, G3RUH, G4NJH, G8IQU, HB9MAO, AA7BQ, N3EQF, KP2BL, W1UD, WN4AZY, W3IS, G8EXV, G0RUR, GM3JZK, G4IFB, N0ED (G3SQX), G3SEK, G0CUZ, G7LFC, 9M2CR, OH5IY, DL5BCU, G3TZO, G3OAF, G0BAF, VK3UM, G3NKS, G3PHO, EA2LU, K7BV, K2UYH, W6/PA0ZN, WA1LOU, G4HXH, and many others.

The BATC (British Amateur Television Club) has now adopted this proposal in its CQ-TV magazine and on its Web Pages, and recommends its members to also adopt it in their own Amateur Radio and Television activities.

  Ian Galpin, G1SMD    1998 April 14th.

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Last modified: 1998-08-09. FP Created
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Year 2000 and ISO 8601.