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*Subject*: **Re: [office-formula] Calculation Settings**

*From*:**"David A. Wheeler" <dwheeler@dwheeler.com>***To*: robert_weir@us.ibm.com, "office-formula@lists.oasis-open.org" <office-formula@lists.oasis-open.org>*Date*: Sat, 16 May 2009 23:19:03 -0400

robert_weir@us.ibm.com wrote: > Here's what I'm thinking: > > We have an abstract machine that does operations on dates. Dates, when > stored, are stored as ISO 8601 strings. We also define explicit and > implicit ways of converting numeric data into dates. The implict coercion > method has one or more parameters, one of which is the date basis. > ... I don't think > we should care. What we really need to define is the type conversion. > > If we state it along those lines (conceptually -- obviously the text would > need to be more fully articulated) would that do the job? Well, they really ARE numbers. For example, ISNUMBER() must return TRUE() for a date or datetime value. I know of no spreadsheet applications that has a true separate date type; I believe all applications simply use numbers, and whether or not it's a date or time or datetime is simply a formatting property of a particular cell. ODF's storing of the 'current cell value' as an ISO date is still very nice; it partly isolates spreadsheets from some of the worst nastiness of epoch values. If describing the operations as a separate type would be the best way to express what's required, then it might still be fine to word it as a "separate" type, if worded carefully. Certainly there are a lot of languages with such types which could be used as a model. Of course, good wording is always the trick :-). Part of the reason the current text is so awkward is because it's trying to work around the obvious problem: Some applications (intentionally) calculate 1900's leap-year incorrectly, while others do it correctly. If the current text isn't as clear as it should be, then by all means, please, propose an alternative! --- David A. Wheeler

**Follow-Ups**:**Re: [office-formula] Calculation Settings***From:*Andreas J Guelzow <aguelzow@math.concordia.ab.ca>

**References**:**[office-formula] Calculation Settings***From:*Eric Patterson <ericpa@exchange.microsoft.com>

**Re: [office-formula] Calculation Settings***From:*"David A. Wheeler" <dwheeler@dwheeler.com>

**RE: [office-formula] Calculation Settings***From:*Eric Patterson <ericpa@exchange.microsoft.com>

**RE: [office-formula] Calculation Settings***From:*"Andreas J. Guelzow" <aguelzow@math.concordia.ab.ca>

**Re: [office-formula] Calculation Settings***From:*"David A. Wheeler" <dwheeler@dwheeler.com>

**Re: [office-formula] Calculation Settings***From:*"Andreas J. Guelzow" <aguelzow@math.concordia.ab.ca>

**Re: [office-formula] Calculation Settings***From:*robert_weir@us.ibm.com

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