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4.4 KiB
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143 lines
4.4 KiB
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<HEAD>
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<TITLE>Year 2000 issues in FTN software.</TITLE>
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</HEAD>
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<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
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<BODY
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<PRE>
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**********************************************************************
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FTSC FIDONET TECHNICAL STANDARDS COMMITTEE
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**********************************************************************
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Publication: FSP-1009
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Revision: 1
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Title: Year 2000 issues in FTN software
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Author: Michael Hohner, 2:2490/2520.17
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Revision Date: 29 December 1997
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Expiry Date: 29 December 1999
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----------------------------------------------------------------------
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Contents:
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1. Introduction
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2. Generating Fidonet timestamps
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3. Interpreting Fidonet timestamps
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----------------------------------------------------------------------
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Status of this document
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-----------------------
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This document is a Fidonet Standards Proposal (FSP).
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This document specifies an optional Fidonet standard protocol for
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the Fidonet community, and requests discussion and suggestions for
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improvements.
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This document is released to the public domain, and may be used,
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copied or modified for any purpose whatever.
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Abstract
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--------
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The year 2000 causes problems in many computer programs which use
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two-digit year numbers. Current Fidonet software faces the very same
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problems. This FSP specifies procedures which enable FTN software to
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run without problems after the year 2000.
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1. Introduction
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---------------
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Software using two-digit year numbers may cause problems in the year
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2000. When the year number rolls over from "99" to "00", some
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software may interpret the resulting year number as "1900" instead
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of "2000". Such programs may contain code like this:
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calendar_year = year_number + 1900; /* wrong! */
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Fidonet software faces the very same problem: the year number in
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packed messages (see FTS-0001) has only two digits. Some programs
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interpreting this number incorrectly may decide that messages from
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the year 1900 are too old and discard them. Other programs probably
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just display a wrong calendar year.
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The long-term solution would be a transition to four-digit year
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numbers. However, this would require new data formats and cause
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every existing software to fail. So a short-term solution is
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required, resulting in only minimal changes in software. This FSP
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contains guidelines for proper year-number interpretation. The
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author encourages all FTN software authors to check their software
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for possible year-2000 problems (and release fixed versions during
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the next three years).
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2. Generating Fidonet timestamps
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--------------------------------
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This should not cause much headache. However, some software may use
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the following algorithm:
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year_number = calendar_year - 1900 /* wrong! */
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This will result in a three-digit year number in 2000 and lead to
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incorrect Fidonet timestamps.
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One correct algorithm is:
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year_number = calendar_year mod 100 /* correct! */
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3. Interpreting Fidonet timestamps
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----------------------------------
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We can make use of the fact that Fidonet didn't exist before 1980,
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i.e. no messages were created before 1980. So any year number
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smaller than 80 can't mean "year 19xx", but can only mean "year
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20xx". One algorithm for correct year number interpretation is:
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if year_number < 80 then
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calendar_year = 2000 + year_number
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else
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calendar_year = 1900 + year_number
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Fidonet software should only use the calendar year for further
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processing, not the year number from the timestamp.
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This solution will work until 2080, giving us another 80+ years to
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finally let some innovation happen in Fidonet.
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A. Contacting the author
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------------------------
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The author may be contacted electronically at the following
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addresses:
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Fidonet: 2:2490/2520.17
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Internet: miho@osn.de
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Suggestions, comments and corrections are always welcome.
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B. History
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----------
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Rev.1, 19971229: Submitted as FSP.
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**********************************************************************
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</PRE>
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