Re: Dates and times

Martin wrote (to the Unicode list):

>On Wed, 26 Feb 1997, Allen B. Reeves wrote:
>
>> Misha and others,
>> 	It is always better to specify date/time information in numbers.  Also,
>> the format YYMMDD:hh:mm:ss:ddd...  lets one compare date/time info mathematically
>
>PLEASE, make that YYYYMMDD:hh:mm:ss:ddd... or even
>...YYYYMMDD:hh:mm:ss:ddd...
>
>Don't use something that has an expected life time of a little more
>than two years.
>
>Regards,	Martin.

Could someone tell me where the ..YYMMDD:hh:mm:ss format comes from?
I'm particularly interested in the ":" between the "DD" and the "hh".
ISO 8601 uses the separator "T" in this position.

Misha