Despite all of the hooplah about Y2K, computer programmers and protocol designers have not really learned from Y2K. Just because a problem seems far off, it should NOT be ignored. 30 years ago, the year 2000 seemed unimaginably far off and many protocols and programs were not designed to deal with it. Now, we see a similar problem on the horizon and we fear that most computer professionals are again looking the other way. Starting with the year 10,000, years will have 5 digits. At least 16 RFCs and one ISO standard specify 4-digit years and countless programs (including those fixed for Y2K) rely on 4-digit years. Given civilization's projected dependence on computers in 8,000 years, the potential for disaster is nearly unlimited. Given the possibility that code and protocols developed today will still be running, we must begin dealing with the Y10K problem immediately. We have developed a proposal to solve the Y10K problem and released it to focus attention on this looming catastrophe. It is available today and can be found in any RFC repository. Its number is RFC2550 and is titled "Y10K and Beyond". We strongly encourage all subscribers to the Risks Digest to read it and heed its message. Steve Glassman [Among other places, this is in the official RFC repository at ftp://ftp.isi.edu/in-notes/rfc2550.txt . PGN] - = - = - = - = - = - = - = - = - = - = - = - = - = - = - = - = - = - = Network Working Group S. Glassman Request for Comments: 2550 M. Manasse Category: Stinkards Track J. Mogul Compaq Computer Corporation 1 April 1999 Y10K and Beyond Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (1999). All Rights Reserved. Abstract As we approach the end of the millennium, much attention has been paid to the so-called "Y2K" problem. Nearly everyone now regrets the short-sightedness of the programmers of yore who wrote programs designed to fail in the year 2000. Unfortunately, the current fixes for Y2K lead inevitably to a crisis in the year 10,000 when the programs are again designed to fail. This specification provides a solution to the "Y10K" problem which has also been called the "YAK" problem (hex) and the "YXK" problem (Roman numerals). 1. Introduction, Discussion, and Related Work Many programs and standards contain, manipulate and maintain dates. Comparing and sorting dates is a common activity. Many different formats and standards for dates have been developed and all have been found wanting. Early date formats reserved only two digits to represent the year portion of a date. Programs that use this format make mistakes when dealing with dates after the year 2000. This is the so-called Y2K problem. The most common fix for the Y2K problem has been to switch to 4-digit years. This fix covers roughly the next 8,000 years (until the year 9999) by which time, everyone seems convinced that all current programs will have been retired. This is exactly the faulty logic and lazy programming practice that led to the current Y2K problem! Programmers and designers always assume that their code will eventually disappear, but history suggests that code and programs are often used well past their intended circumstances. The 4-digit year leads directly to programs that will fail in the year 10,000. This proposal addresses the Y10K problem in a general way that covers the full range of date and time format issues. 1.1 Current approaches A large number of approaches exist for formatting dates and times. All of them have limitations. The 2-digit year runs into trouble next year. The 4-digit year hits the wall in the year 10,000. A 16-bit year runs out in the year 65,536. A 32-bit counter for the number of seconds since 1970 [UNIX] wraps in 2038. A 32-bit counter for the number of milli-seconds since booting crashes a Windows (TM) PC in 49.7 days [Microsoft]. In this specification, we focus on the Y10K problems since they are most common and a large number of existing standards and protocols are susceptible to them (section 7). These standards, and new proposals on their way, will lead to a serious world-wide problem unless efforts are made now to correct the computing, government, and business communities. Already, a small cottage industry is popping up to deal with the Y10K problem [YUCK]. We encourage these efforts and, in the coming years, this effort can only grow in size and importance. 1.2 A Fixed Format Y10K Fix At the time of this writing, only one proposal [Wilborne] directly deals with the Y10K problem. In that proposal, dates are represented as decimal numbers with the dates compared numerically. The proposed format is simply YYYYYMMDD - i.e. 5-digit years. To allow numerical comparison of dates, this representation requires a completely fixed representation for the date. There can be no optional fields, the date resolution is limited to the granularity of one day, and this solution fails in the year 100,000 (Y100K). 1.2.2 Limitations of Numerical Comparison While sufficient for the specific Y10K problem, this solution is limited. Even if extended for 6-digit years, it fails on 32-bit systems (and future 32-bit system emulators) after the date represented by the number 2147481231 (December 31, 214748) leading to a Y214749 problem. Similarly, 64-bit and 128-bit systems also will fail, although somewhat later (after December 31, 922,337,203,685,477 and December 31, 17,014,118,346,046,923,173,168,730,371,588,410 respectively). 1.2.3 Granularity Issues The granularity problems of a fixed format date can be improved by extending the date format to include greater precision in the date. However, since numerical comparison of dates requires a fixed representation date, an extended format can not provide sufficient resolution for all foreseeable needs. For instance, if the precision were extended to the femto-second range the date format would become YYYYYMMDDHHMMSSmmmuuunnnpppfff (year, month, day, hour, minute, second, milli-second, micro-second, nano-second, pico-second, and femto-second). The additional 21 digits of this format limit the set of representable dates. Compared to 1.2.2, the 32-bit and 64-bit forms of the date are instantly exceeded, while the 128-bit version would be viable - expiring on December 31, 17,014,118,346,046. 18.104.22.168 Extrapolation of Future Granularity Issues However, a simple extrapolation of Moore's law shows that even femto-second resolution will soon be inadequate. Projecting current CPU clock speeds forward, a femto-second clock speed will be achieved in only 30 years. And, by the year 10,000 the projected clock speed of the Intel Pentium MMDCLXVI (TM) will be approximately 10 ** (- 1609) seconds. This discussion clearly shows that any fixed-format, integer representation of a date is likely to be insufficiently precise for future uses. 22.214.171.124 Floating Point Is No Solution The temptation to use floating point numbers to represent dates should be avoided. Like the longer fixed-format, integer representations of the date, floating point representations merely delay the inevitable time when their range is exceeded. In addition, the well known problems of real numbers - rounding, de-normalization, non-uniform distribution, etc. - just add to the problems of dealing with dates. 2 Structure of Y10K Solution Any Y10K solution should have the following characteristics. 2.1 Compatibility The format must be compatible with existing 4-digit date formats. Y2K compliant programs and standards must continue to work with Y10K dates before the year 10,000. Y10K compliant programs can gradually be developed over time and coexist with non-Y10K compliant programs. 2.2 Simplicity and Efficiency Y10K dates must allow dates after 10,000 to be easily identified. Within a program, there must be a simple procedure for recognizing the Y10K dates and distinguishing them from legacy dates. 2.3 Lexical Sorting Y10K dates must be sortable lexically based on their ASCII representation. The dates must not require specialized libraries or procedures. 2.4 Future Extensibility Y10K dates must support arbitrary precision dates, and should support dates extending arbitrarily far into the future and past. Y10K dates from different eras and with different precisions must be directly comparable and sortable. 2.4.1 Environmental Considerations The known universe has a finite past and future. The current age of the universe is estimated in [Zebu] as between 10 ** 10 and 2 * 10 ** 10 years. The death of the universe is estimated in [Nigel] to occur in 10 ** 11 - years and in [Drake] as occurring either in 10 ** 12 years for a closed universe (the big crunch) or 10 ** 14 years for an open universe (the heat death of the universe). In any case, the prevailing belief is that the life of the universe (and thus the range of possible dates) is finite. 2.4.2 Transcending Environmental Considerations However, we might get lucky. So, Y10K dates are able to represent any possible time without any limits to their range either in the past or future. Y10K compliant programs MAY choose to limit the range of dates they support to those consistent with the expected life of the universe. Y10K compliant systems MUST accept Y10K dates from 10 ** 12 years in the past to 10 ** 20 years into the future. Y10K compliant systems SHOULD accept dates for at least 10 ** 29 years in the past and future. 3 Syntax Overview The syntax of Y10K dates consists of simple, printable ASCII characters. The syntax and the characters are chosen to support a simple lexical sort order for dates represented in Y10K format. All Y10K dates MUST conform to these rules. Every Y10K date MUST begin with a Y10K year. Following the year, there MAY be an arbitrary sequence of digits. The digits are interpreted as MMDDHHMMSSmmmuuunnnpppfff... (month, day, hour, minute, second, milli-second, micro-second, nano-second pico-second, femto-second, etc. - moving left to right in the date, digits always decrease in significance). All dates and times MUST be relative to International Atomic Time (TAI) [NRAO]. When comparing dates, a date precedes every other date for which it is a prefix. So, the date "19990401000000" precedes the date "19990401000000000". In particular, dates with the format YYYYMMDD are interpreted to represent the exact instant that the day begins and precede any other date contained in that day. 3.1 Years 1 - 9999 The current 4-digit year syntax covers all years from 1000 - 9999. These years are represented as 4 decimal digits. Leading 0's MUST be added to the years before 1000 to bring the year to 4 digits. Files containing legacy pre-Y1K [Mike] dates will have to be converted. 3.2 Years 10,000 through 99,999 Four digits are not sufficient to represent dates beyond the year 9999. So, all years from 10,000 - 99,999 are represented by 5 digits preceded by the letter 'A'. So, 10,000 becomes "A10000" and 99,999 dates with 5-digit years will follow all dates with 4-digit years (for example, "A10000" will sort after "9999"). This gives us the sort and comparison behaviour we want. 3.3 Years 100,000 up to 10 ** 30 By a simple generalization of 3.2, 6-digit years are preceded by the letter 'B', 7-digit years by 'C', etc. Using just the 26 upper-case ASCII characters, we can cover all years up to 10**30 (the last year representable is "Z999999999999999999999999999999"). Again, since the ASCII characters are sorted alphabetically, all dates sort appropriately. 3.4 Years 10 ** 30 and beyond (Y10**30) As discussed in 2.4.1, the end of the universe is predicted to occur well before the year 10 ** 30. However, if there is one single lesson to be learned from the current Y2K problems, it is that specifications and conventions have a way of out living their expected environment. Therefore we feel it is imperative to completely solve the date representation problem once and for all. 3.4.1 Naive Approach for Y10**30 Problem The naive solution is to prepend a single '^' (caret) - caret sorts after all letters in the ASCII order) before all years from 10 ** 30 to 10 ** 56. Thus the year "Z999999999999999999999999999999" is followed by the year "^A1000000000000000000000000000000". Similarly, all years from 10 ** 56 to 10 ** 82 get one more caret. So, the year "^Z99999999999999999999999999999999999999999999999999999999" is followed by the year "^^A100000000000000000000000000000000000000000000000000000000". This scheme can be extended indefinitely by prepending one addition caret for each additional factor of 10 ** 26 in the range of the year. In this approach, the number of digits in a date that are used to represent the year is simply: 26 *
http://www.umsl.edu/~bwilking/assign/drake.html [Microsoft] SNMP SysUpTime Counter Resets After 49.7 Days http://support.microsoft.com/support/kb/articles/Q169/8/47.asp [Mike] Y1K http://lonestar.texas.net/~mdlvas/y1k.htm [Nigel] Nigel's (en)lighening tour of Thermodynamics for Economists ;-) http://www.santafe.edu/~nigel/thermo- primer.html [NRAO] Astronomical Times http://sadira.gb.nrao.edu/~rfisher/Ephemerides/times.html [RFC] Here are all the online RFCs. Note: this is a LONG menu. http://info.internet.isi.edu/1s/in-notes/rfc/files [UNIX] Year 2000 Issues http://www.rdrop.com/users/caf/y2k.html [Wilborne] PktCDateLig http://www3.gamewood.net/mew3/pilot/pocketc/pktcdate/index.html [YUCK] Y10K Unlimited Consulting Knowledgebase http://www.loyd.net/y10k/index.html [Zebu] The Search for H0 http://zebu.uoregon.edu/1997/ph410/l6.html 11 Authors' Addresses Steve Glassman Compaq Systems Research Center 130 Lytton Avenue Palo Alto, CA 94301 USA Phone: +1 650-853-2166 EMail: email@example.com Mark Manasse Compaq Systems Research Center 130 Lytton Avenue Palo Alto, CA 94301 USA Phone: +1 650-853-2221 EMail: firstname.lastname@example.org Jeff Mogul Compaq Western Resarch Lab 250 University Avenue Palo Alto, CA 94301 USA Phone: +1 650-617-3300 EMail: email@example.com 12. Full Copyright Statement Copyright (C) The Internet Society (1999). All Rights Reserved. This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into languages other than English. The limited permissions granted above are perpetual and will not be revoked by the Internet Society or its successors or assigns. This document and the information contained herein is provided on an "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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