[Digikam-devel] [Bug 304077] XMP metadata interoperability problem and inconsistency

[Jean-François Rabasse]

https://bugs.kde.org/show_bug.cgi?id=304077

--- Comment #3 from Jean-François Rabasse <jean-francois.rabasse at wanadoo.fr> ---
(In reply to comment #2)
> Sorry, the dc properties are all lowercase. (in contrast, tiff: properties
> start uppercase). Please refer to the XMP specification.
> The XMP specification does not state anything about case sensitivity, so I
> agree with you that XMP is case sensitive as XML is. Which means the sample
> image contains an entry which is not defined in the dc namespace.
> 
> Which software is writing dc.Title?

Hello Marcel,

Thanks for feedback. I've also investigated and it appears the problem comes
from a historical DCMI inconsistency.
As they say themselves, (cf. http://dublincore.org/documents/naming-policy/)
"In 1998, the Dublin Core element set was published using Names (at the time
called Labels) which had a leading uppercase character, e.g. Title and Creator
[RFC2413]. In October 2000, the DCMI Advisory Committee decided to change the
Names of elements to lowercase in order to bring DCMI practice into line with
conventions widely (though not universally) followed in existing Dublin Core
applications and in the XML and RDF/XML communities more generally.

Unfortunately, this decision was propagated throughout DCMI documentation only
after some delay [DC-ELEMENTS]. In the meantime, the Dublin Core Metadata
Element Set had progressed through formal standardization channels for
recognition first as NISO Z39.85-2001 and CEN Workshop Agreement CWA 13874,
then as ISO 15836 -- with element Names starting in uppercase [ISO15836]."

So, they started with capitalized elements names, then changed their mind to
all lowercase at a moment the ISO standard was already on its way. Too bad.

I suggest to close this issue, as it is clearly not an applications issue. I
don't know, due to this formal inconsistency, how many images on the earth may
embed a xmp.dc.Title instead of xmp.dc.title. 
As DCMP suggest (IMHO in a somewhat casual way) "In practice, this suggests
that applications are well advised to normalize case when parsing terms for
identity comparisons", I've fixed my immediate problem, in my reading program,
by checking both syntaxes.
Something like :
 - get xmp.dc.title
 - if non existent or empty, get xmp.dc.Title
This solves my problem and I can live with, that way :)

Regards
Jean-François

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