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I've came across what appears to be a date format from a legacy database application.

I don't have access to the code that generated it, just have examples corresponding to certain Holiday messages.

I am trying to convert these into standard dates. I hope that this is a standard, perhaps obscure or long obsolete date format.

The dump appeared to be in big-endian byte-order and 7-bit clean

Roughly it seems to start at the Unix epoch ( Jan 1 1970 ) at 00 00 00. As per similar questions, all data is in Hex.

There appear to be two numbers that never appear in the rightmost column, but that is possibly my data set because one of them does appear in the middle column.

  • Jul 4 2001, 03 4E 7B <-- fixed typo
  • Dec 24 2001, 03 55 76
  • Jul 4 2002, 03 5D 52
  • Dec 24 2002, 03 64 4D
  • Jul 4 2003, 03 6C 2A
  • Dec 24 2003, 03 73 25
  • Dec 24 2004, 04 02 02
  • Jul 4 2005, 04 09 5F
  • Dec 24 2005, 04 10 5A
  • Dec 24 2006, 04 1F 31
  • Jul 4 2007, 04 27 0E
  • Dec 24 2007, 04 2E 09
  • Dec 24 2008, 04 3C 66
  • Dec 24 2009, 04 4B 3D
  • Jul 4 2010, 04 53 1A
  • Dec 24 2010, 04 5A 15
  • Dec 24 2011, 04 68 6D
  • Dec 24 2012, 04 77 4A
  • Dec 24 2013, 05 06 21
  • Jul 4 2014, 05 0D 7E <- fixed typo
  • Jul 5 2014, 05 0E 03
  • Jul 6 2014, 05 0E 08
  • Jul 7 2014, 05 0E 0E
  • Jul 8 2014, 05 0E 13
  • Jul 9 2014, 05 0E 18
  • Dec 24 2014, 05 14 79

Update to add another sequence of dates:

Feb 19 1996  03 00 03
Mar 15 1996  03 01 03
Apr  9 1996  03 02 04
May  3 1996  03 03 00
May 20 1996  03 04 01
Sep 05 1996  03 08 04 
Sep 30 1996  03 09 04 
Oct 24 1996  03 0a 00 
Nov 10 1996  03 0b 01
Jan  1 1997  03 0d 02
Feb  1 1997  03 0e 03
Feb 26 1997  03 0f 04
Apr 16 1997  03 11 00
May 11 1997  03 12 01
Jun  5 1997  03 13 01
Jun 30 1997  03 14 02 
Jul 25 1997  03 15 03 
Aug 19 1997  03 16 04 
Nov  1 1997  03 19 01
Nov 26 1997  03 1a 02 
Jan 15 1998  03 1c 03
Feb  9 1998  03 1d 04 
Mar 30 1998  03 1f 00
..
Jan 11 2004  03 74 02
Feb  5 2004  03 75 02 
Mar  1 2004  03 76 03
Mar 26 2004  03 77 04 
Apr 19 2004  03 78 00
May 14 2004  03 79 00
Jun  8 2004  03 7a 01 
Jul  3 2004  03 7b 02
Jul 28 2004  03 7c 03 
Aug 22 2004  03 7d 03
Sep 16 2004  03 7e 04
Oct 10 2004  03 7f 00 
Nov  4 2004  04 00 00 
Nov 29 2004  04 01 01 
Dec 24 2004  04 02 02   
Jan 18 2005  04 03 03
  • 1
    Can you dump more sample values? – sudhackar Apr 3 '18 at 11:18
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After converting the HEX to 0 and 1, trying to look for a pattern, I think that it's not a coded date but a variation on number of days from a base date. I found two abnormalities - (Jul 4 2001, 03 5E 7B and Dec 24 2001, 03 55 76) and (Jul 4 2014, 05 0E 7E and Jul 5 2014, 05 0E 03) where the later date has a smaller hex value, which lead me to wonder if there are more dates so we can try to understand this pattern.

  • Thank you for looking - I believe it's (roughly) 5 times days since 1970-01-01, split into ASCII chars. The abnormalities you identified were my typos and I apologize. – GeeWhiz Apr 6 '18 at 14:46
  • Can you add 6-10 consecutive dates that start at one month and end at another? i.e. NOV 25 till DEC 05 – JTS Apr 9 '18 at 5:38

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