Re: Fwd: Re: [office-formula] Straw poll - slug (and lightyear)

[Patrick Durusau <patrick@durusau.net>]

David,

On 4/6/2010 5:33 PM, David A. Wheeler wrote:

E1NzGP4-0000Is-Lu@fenris.runbox.com" type="cite">

"Andreas J. Guelzow":
  

We say "Light-year, the distance light travels in a year of 365.25 days"
which isn't exact at all (we probably mean in vacuum...).
    

Ah, that's an error in the spec. It should *definitely* say "distance light travels, in a vacuum,
in a year of 365.25 days".  In general, we should be giving exact values where we can.

PATRICK: Please insert ", in a vacuum," after "light travels", at that point.
Let me know if you want me to create a separate JIRA comment for this.

  

No need, will correct. I am sure people calculating their mileage allowances need an exact value. ;-)

BTW, the "*" made me look for the explanation and I find:

Unit symbols in cells marked with * shall support decimal prefixes, and unit symbols in cells marked with † shall support binary prefixes; evaluators should not support prefixes for other unit symbols.

I am not going to post a JIRA issue but clearly unit symbols don't support any sort of prefixes. Evaluators might.

Re-writing to say:

Evaluators shall support decimal prefixes for unit symbols marked with * and binary prefixes for unit symbols marked with †. Evaluators should not support prefixes for other unit symbols.

I am not happy with the final sentence but will try to think of a better way to say that.

Hope you are having a great day!

Patrick

E1NzGP4-0000Is-Lu@fenris.runbox.com" type="cite">

WARNING: Technical nitpick ahead:
The distance light travels in a year, in a vacuum, *is* exact; the meter is actually defined
in terms of speed of light in a vacuum. And while an Earth year isn't exactly 365.25 days, for purposes of a
light-year, that's the exact value of the "year". It's not well-documented, but astronomers
use this "standard year approximation" of 365.25 days when stating light-years.
And since a day is exactly 24*60*60 seconds, this has an exact value.
I actually had to track that down, and I'm pretty sure I posted my citations
(though I can't remember where they are right now).  If anyone knows differently,
please let us know now.

--- David A. Wheeler

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-- 
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)