----- Original Message ----- 
From: "Mike Stevens" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Thursday, March 08, 2007 12:24 AM
Subject: Re: [canals-list] Re: Boat trouble with GPS positioning


> On Wednesday, March 07, 2007 6:01 PM [GMT+1=CET],
> Ken Hornstein <[EMAIL PROTECTED]> wrote:
>
>>  Strictly speaking, data is the plural of datum, and should be used
>>  with a plural verb (like facts). However, there has been a growing
>>  tendency to use it as an equivalent to the uncountable noun
>>  information, followed by a singular verb. This is now regarded as
>>  generally acceptable in American use, and in the context of
>>  information technology. The traditional usage is still preferable,
>>  at least in Britain, but it may soon become a lost cause.
>
>> Within the context of GPS I have always seen people refer to the
>> plural
>> of "datum" as "datums" (e.g., http://www.gpsinformation.net); I have
>> _never_ seen anyone refer to multiple GPS datums as "data".  Several
>> online dictionaries say for datum, "plural: data or datums", and at
>> least one reference I found says "In rare instances, the plural
>> datums may be used, specifically when datum refers to a reference or
>> standard value".
>
> The problem, as I see it, is that the Latin word 'datum' with its plural
> 'data' has, since its incorporartion into English, diverged into two quite
> different meanings, one of which makes no sense to me.
>
> Being used, as a mathematician, to the use of "data" to mean a set of
> numbers, I feel uncomfortable with the current use of "datum" in GPS  and
> allied topics.  I believe this started out with the "OS Datum" which
> specified that the place from which altitdue was measured by the Ordnance
> Survey was the mean high water spring tide level in a specific location 
> (or
> something like that).  I was perfectly happy with that  -  it was a given
> single item of information and I could accept "datum" as a proper word for
> it.  But to extend that use to call a mathematical model of the Earth's
> surface a "datum" strikes me as flying in the face of linguistic sense.
> It's not a datum, it's an infinite set of data with a three-dimensional
> structure.
>
> Mike Stevens

Beautifully articulated, Mike! I now realise that was my problem with it, 
but I am saving my brainpower and big words for something else at the 
moment.

Dorothy 


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