RE: International Designation and Year 2000

Bjoern Gimle (
Tue, 1 Oct 1996 00:19:16 +0200 (MET DST)

>Ed Cannon wrote: 
>>My (first) question regarding the International Designation format is,
>>how will it be handled beginning 1 Jan. 2000?  Won't it become almost 
>>a necessity to use all four digits of the year?

Ted Molczan replied:
>I do not know what NORAD plans to do, but since 
>artificial satellites were not launched prior to 
>1957, they could keep the same format, and simply 
>let the year roll over to 00 in 2000. That would 
>postpone the problem to 2057. 
>Of course software that simply adds yy to 1900 
>would have to be re-written, but that would be 
>true even if a yyyy format were adopted.
>>Maybe the "sky-is-falling" alarmists have a point about the year 2000
>>and computer software problems.... 

The problem has (at least) three levels:

We can manually determine that a number less than 57ddd (/57mmdd)
refers to the years 2000-2056, as far as satellites go.

Our software can cope with the problem in a similar way - does it ?
Many databases and software development environments have an internal
date/time format, e.g using days and decimals since 1900 or 1855 or...
Mine (CA Realizer) does, and it accepts, and automatically
converts YYMMDD, M/D/YY	M/D/YYYY, D-MMM-Y and D-MMM-YYYY to the correct
internal format. (I convert YYDDD to YY0101, then add DDD-1 days using
the built-in date arithmetic). 
The roll-over point can be adjusted by the user/programmer : 
"_CenturySplit	A real scalar that indicates which dates are for
the 20th century and which are for the 21st century. Any years
entered as a two digit number that are larger than this value
are considered to be part of the 20th century.  Any years smaller
than this value are considered to be part of the 21st century. " 

Or, the program has to be changed so it won't throw away elsets after
2000.0 for being older than 1999, computing the age of a 1999 elset
correctly for predictions, formatting the output dates correctly,.....

But as Ted also points out, if they adopt a four digit year format ,
the software probably must be rewritten anyway... 

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