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> Was it? I've never heard of that date in connection with COBOL before. Which COBOL? COBOL for AIX: > The beginning of the Lilian date range is Friday 15 Oct

> Was it? I've never heard of that date in connection with COBOL before. Which COBOL? COBOL for AIX: > The beginning of the Lilian date range is Friday 15 October 1582, the date of adoption of the Gregorian calendar. Lilian dates before this date are undefined. * https://www.ibm.com/docs/en/cobol-aix/5.1?topic=times-feedback-token https://www.ibm.com/docs/en/cobol-aix/5.1?topic=times-feedba... COBOL for z/OS > DATE-OF-INTEGER […] A positive integer that represents a number of days succeeding December 31, 1600, in the Gregorian calendar. The valid range is 1 to 3,067,671, which corresponds to dates ranging from January 1, 1601 thru December 31, 9999.* * https://www.ibm.com/docs/en/cobol-zos/6.4?topic=functions-date-integer https://www.ibm.com/docs/en/cobol-zos/6.4?topic=functions-da... So two COBOLs, from the same vendor (IBM), have different epochs. More: > CEECBLDY: Converts character date value to the COBOL Integer format. Day one is 01 January 1601 and the value is incremented by one for each subsequent day. […] > CEEISEC: Converts binary year, month, day, hour, minute, second, and millisecond to a number representing the number of seconds since 00:00:00 14 October 1582 * https://www.ibm.com/docs/en/zos/2.5.0?topic=services-basics-using-date-time https://www.ibm.com/docs/en/zos/2.5.0?topic=services-basics-... See also: > I have seen COBOL epochs in active use of 1600.01.01, 1875.05.24, 1900.01.01, 0000.00.00, 1970.01.01, 2000.01.01. and others. * https://old.reddit.com/r/ISO8601/comments/1ipikj5/those_who_do_not_expect_iso8601_shall_be_punished/mcychah/ https://old.reddit.com/r/ISO8601/comments/1ipikj5/those_who_...

skissane 2y ago
You cite two COBOL implementations which use 1582 or 1600/1601 as epoch dates – that's not evidence that any COBOL uses 1875-05-20 as an epoch date. Then you cite an pseudonymous Reddit comment which claims they've seen a COBOL implementation using 1875-05-24 (not actually 1875-05-20, although maybe they meant to say 20 and the 24 is a mistake) – but can't even tell us what it is named. Maybe, somewhere out there, is a COBOL implementation which actually does use 1875-05-20: but if nobody can name it, we don't even know that it exists. And even if someone actually succeeds in digging up the name of a COBOL implementation using 1875-05-20 as an epoch date, can we be sure that is actually the COBOL implementation SSA is using?

skissane 2y ago

You cite two COBOL implementations which use 1582 or 1600/1601 as epoch dates – that's not evidence that any COBOL uses 1875-05-20 as an epoch date. Then you cite an pseudonymous Reddit comment which claims they've seen a COBOL implementation using 1875-05-24 (not actually 1875-05-20, although maybe they meant to say 20 and the 24 is a mistake) – but can't even tell us what it is named. Maybe, somewhere out there, is a COBOL implementation which actually does use 1875-05-20: but if nobody can name it, we don't even know that it exists. And even if someone actually succeeds in digging up the name of a COBOL implementation using 1875-05-20 as an epoch date, can we be sure that is actually the COBOL implementation SSA is using?