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This is great stuff. It sounds like there is a real distinction to be made between the data central to the apis and the user-defined properties. Also, as time and compatibility allow, we should probably change what we were calling metadata to be called properties or somesuch.

"Jay Pipes" <jaypipes at gmail.com> said:

> On Mon, Feb 28, 2011 at 10:45 PM, Jay Pipes <jaypipes at gmail.com> wrote:
>> for those of a like-minded curiosity about these things. From the
>> wikipedia article on this same subject:
>>
>> "The term Metadata is an ambiguous term which is used for two
>> fundamentally different concepts (Types). Although a trite expression
>> "data about data" is often used, it does not apply to both in the same
>> way. Structural metadata, the design and specification of data
>> structures, cannot be about data, because at design time the
>> application contains no data. In this case the correct description
>> would be "data about the containers of data". Descriptive metadata on
>> the other hand, is about individual instances of application data, the
>> data content. In this case, a useful description (resulting in a
>> disambiguating neologism) would be "data about data contents" or
>> "content about content" thus Metacontent. Descriptive, Guide and the
>> NISO concept of Administrative metadata are all subtypes of
>> metacontent."
> 
> And for those wondering why the Glance project uses the term
> "metadata" to describe data about the image, we, too, have a similar
> terminology problem:
> 
> We delineate between the image *data*, which is the raw image file
> itself, and image *metadata*, which is really data about the image
> (like disk format, status, etc). To make matters worse, we have the
> concept of image *properties* which are free-form key/value pairs
> attached to the image.
> 
> So, neither Glance nor Nova uses the term *metadata* properly, for
> what it's worth :)
> 
> -jay
> 
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