[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]
Subject: RE: [office-formula] serial number? Don't we mean serial date?
This is really very simple. We don't need to refer to serial dates at all. There are dates and there are numbers. The _only_ thing we need to state in Part 2 is what happens when a date value is used in the context of a number. In that case there is an implicit type conversion to a number, which is the number of whole days and the fraction of a day since an implementation-defined fixed point in time, called the epoch. If we state only that much, then we encompass implementations, like Excel, where all user-dates are stored as numbers, as well as OpenOffice, where user entered dates are stored as ISO 8601 dates. I think OpenFormula should be agnostic to that decision if it can. That decision is really an application/user convention, not an OpenFormula issue. It concerns what happens to a user-entered string and how it is stored. Excel does it one way, OpenOffice another. But that is outside of OpenFormula, which concerns how those stored formulas are calculated. The semantics of calculations on dates is a bit murky. Certainly adding a constant to a date, and subtracting two dates, these have obvious interpretations. But spreadsheets also allow you to multiply two dates, etc. Excel let's you calculation the value of SIN(DATE(2010,1,27)). We can offer no interpretation to that other than a date is implicitly converted to a number, as stated above. Saying anything more gets us into trouble. The format of a number in a date format is the other side of the coin for the implicit conversion question. But I think that is a Part 1 question for the presentation of table cell formats, but not a Part 2 question. -Rob From: "Dennis E. Hamilton" <dennis.hamilton@acm.org> To: "'Patrick Durusau'" <patrick@durusau.net>, <office-formula@lists.oasis-open.org> Date: 01/27/2010 02:28 PM Subject: RE: [office-formula] serial number? Don't we mean serial date? I had been calling them ORDINAL DATES, but I realize they are really ordinal DAYS. You can call them SERIAL DAYS (but not dates). I think that would be fine. They are not dates, they are just intervals of days (including fractions thereof). I think these only become dates when taken with an origin date and the calendar mapping that goes with that origin date. Since different hostings will have different defaults for this, and some will allow selection among a variety of origin dates and calendar mappings (usually document-global and not changeable except at serious risk). The value of a cell holding such an ordinal day may be displayed in a number of ways (hh:mm is a format I use regularly, as is yyyy-mm-dd) as specified for the presentation format of the cell. The second (yyyy-mm-dd) requires an understood origin date and calendar mapping. In the spreadsheets I work with regularly, the cell value is still a Number and it may even be determined by a formula. The value of a cell having specific type date (or date-time) will presumably use any associated origin date and calendar mapping to make an ISO 8601 or other standard date-time representation for its value, with that conversion done as required by the OpenFormula hosting. Likewise, values of cells of type date, and constants of date form (not sure OpenFormula has those), would be automatically convertible to serial days by reference to the prevailing origin date and calendar mapping. - Dennis -----Original Message----- From: Patrick Durusau [mailto:patrick@durusau.net] Sent: Wednesday, January 27, 2010 10:50 To: office-formula@lists.oasis-open.org Subject: [office-formula] serial number? Don't we mean serial date? Greetings! I am doing triage on the data types and keep running into date being referred to as a serial number? Surely we mean serial date? But it happens so often that I wanted to ask before changing it. Hope everyone is having a great day! Patrick -- Patrick Durusau patrick@durusau.net Chair, V1 - US TAG to JTC 1/SC 34 Convener, JTC 1/SC 34/WG 3 (Topic Maps) Editor, OpenDocument Format TC (OASIS), Project Editor ISO/IEC 26300 Co-Editor, ISO/IEC 13250-1, 13250-5 (Topic Maps) --------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php --------------------------------------------------------------------- To unsubscribe from this mail list, you must leave the OASIS TC that generates this mail. Follow this link to all your TCs in OASIS at: https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
[Date Prev] | [Thread Prev] | [Thread Next] | [Date Next] -- [Date Index] | [Thread Index] | [List Home]