Title: Report from public comment period on Dublin Core RDF expression
Creator: Mikael Nilsson
Note: This text of a wiki document,
http://dublincore.org/architecturewiki/DCRDFTaskforce/PublicCommentJune2006,
was created for preservation purposes on 2007-03-29
(version last edited 2006-07-06 09:45:37 by MikaelNilsson).
Period: 30 May - 30 June 2006
The following is a report of the feedback received during the
public comment period on the new Working Draft "Expressing
Dublin Core using the Resource Description Framework". A
summary of the discussions and proposals for moving forward
are presented in the sections below.
----------------------------------------------------------------------
The consequences of adding domains and ranges to DCMI
properties
Some concern has been raised concerning the proposal to
add ranges and domains to the definitions of the DCMI
properties. While strictly not part of this public comment
period, the possibility of adding domains and ranges has been
explicitly recognized in the new Working Draft. If domains
and ranges are added, it is also clear that the RDF expression
of certain metadata constructs (such as for dc:creator) will
be different as compared to earlier RDF expressions from
the DCMI. In particular, several uses of literal strings as
direct values of properties will be made invalid. Based on
Swoogle statistics on the usage of DCMI properties, it is
clear that a vast majority of uses of the 15 core elements
in RDF are literal uses, and hence problematic.
Concern has also been raised that the notions of domains and
ranges are not part of the DCAM.
Proposals
* We need to be very clear that the new expression represents a
closer conformance to the DCAM, and not the other way around.
* It is also important that we are clear regarding the fact that
value strings may still be used to represent the value of a DCMI
property, regardless of range.
* Domains and ranges should be acknowledged in a future version of
the DCAM.
* The discussion on domains and ranges in the draft needs some
improvement, especially concerning the consequences of not
specifying a value type.
* A proposal has been put forward to only apply the new domains and
ranges to properties in the "terms" namespace (including terms
copied from the "1.1" namespace), to lessen the effect on legacy
metadata.
References
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0606&L=dc-architecture&T=0&P=5526
* http://dublincore.org/documents/dc-rdf-notes/#sect-3
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0606&L=dc-architecture&T=0&P=5163
----------------------------------------------------------------------
The relationship between encoding schemes and the corresponding
RDF concepts
This comment period about expressing DCAM-based metadata in RDF
has revived an older discussion about the status of "vocabulary
encoding schemes" (VES) in the DCAM itself. Both the Proposed
Recommendation from 2002 on expressing qualified Dublin Core
in RDF and the DCAM itself model a VES as "the type of a
value". This approach has been followed in the current DC-RDF
draft, which uses the "rdf:type" property to express VESs.
Traditionally, the function of VES has been
to "indicate that the value is a term from a
controlled vocabulary" (see the [WWW]principles
document), and the comment period has made clear that this
traditional definition does not fully overlap with the RDF
notion of Class, which encompasses non-vocabulary-like entities
such as Person and Date.
A proposal has been put forward to modify the DCAM in order to separate
the notions of "vocabulary encoding scheme" and "value type", which in
the current version of the DCAM are seen as equivalent.
Proposals
* Change the DCAM to separate the notions of "value type" from
"vocabulary encoding scheme".
* Modify the Draft DC-RDF expression to separate "value type" from
VES, using a new RDF property, e.g. "dcrdf:inScheme".
* Withhold the draft until clarification of the DCMI "encoding
schemes" has been introduced, especially regarding if they are of
type VES or SES.
References
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0606&L=dc-architecture&T=0&P=1211
* http://dublincore.org/architecturewiki/AMIssues#head-3b6b8af3b9273893a16037aed1b3b1ca1334e7bc
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0510&L=dc-rdf-taskforce&T=0&P=61
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0606&L=dc-architecture&T=0&P=5163
----------------------------------------------------------------------
The use of rdf:value
It has been suggested that the proposed new RDF property
"dcrdf:valueString" would be dropped. Instead the rdf:value property
could be used. This would allow for partial compatibility with the
existing Qualified Dublin Core RDF expression. Note that the proposed
"dcrdf:valueString" RDF property was intended to be a sub-property of
rdf:value, so much of the same semantics would be retained.
It has also been suggested that dcrdf:valueString overlaps too much with
using a dc:title in a related description of the value. There is some
merit to the argument, even though the value of dc:title is not
necessarily a "value representation". Certainly it is the case that an
application looking for text for indexing of the value would look at
both rdf:value, dc:title and possibly other properties.
Proposals
* Revert back to using rdf:value for value strings.
References
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0606&L=dc-architecture&T=0&P=1071
* http://dublincore.org/architecturewiki/DCRDFTaskforce/DCRDFIssues#head-ca100afa3355ef06c589a811ef2804c703286446
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0605&L=DC-ARCHITECTURE&P=R1125&D=0&I=-3&T=0
----------------------------------------------------------------------
The use of datatyped literals as objects of RDF statements
The use of literal strings as direct values of RDF properties is still
not fully understood. Note that using value strings in general is
relatively unproblematic, even when used in combination with Syntax
encoding schemes (SES). This issue has to do with the case when the
range of a property allows for literal values (such as possibly dc:title
and maybe dc:date), especially when that value is combined with a syntax
encoding scheme. It is currently somewhat unclear what the precise
interactions between ranges, value types, VES, SES and literal values are.
As this issue is heavily influenced by the decision on the value type
and VES issue mentioned above, a final solution needs to wait for that
issue to be finalized.
Proposals
* Retains current text, but make sure the consequences with respect
to value type, VES and SES are understood.
* Revisit this issue once the other issues have been sorted out.
References
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0606&L=dc-architecture&T=0&P=1071
----------------------------------------------------------------------
The use of dc:type vs. rdf:type
It was discussed whether using dc:type in RDF metadata was recommended,
as the semantics overlap nearly or completely with rdf:type, especially
after the introduction of a range of "Class" for dc:type. Using rdf:type
would certainly increase interoperability with other RDF metadata.
Proposals
* Recommmend the use of rdf:type in RDF metadata, together with an
explanation that it is equivalent to dc:type for a DC application.
* Revisit this issue after the introduction of domains and ranges of
DCMI properties, to make sure the semantics really match.
References
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0605&L=DC-ARCHITECTURE&P=R1805&D=0&I=-3&T=0
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0606&L=dc-architecture&T=0&P=1071
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0606&L=dc-architecture&T=0&P=5163
----------------------------------------------------------------------
The use of rich representations
Several issues have been brought up regarding rich representations:
* Can we embed anything other than XML in an RDF document? No,
currently all other rich representations need to stored externally.
* Can we put a language tag or SES on rich representations? Not
currently, and not according to the DCAM.
These issues are really DCAM issues. The DCAM s unclear on the exact
nature of rich representations, and the current wording in the DC-RDF
draft is a best-effort formulation.
Proposal
* Retain current text in DC-RDF.
* Revisit after any changes in DCAM are introduced.
References
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0605&L=DC-ARCHITECTURE&P=R1125&D=0&I=-3&T=0
* http://dublincore.org/architecturewiki/AMIssues#head-9c296de12340944dba792c52c99eb19718ee1acf
----------------------------------------------------------------------
Using syntax encoding schemes and language tags simultaneously
Currently, the DCAM allows value strings to carry both a language tag
and a syntax encoding scheme, while the draft DC-RDF expression does not
allow this.
Proposals
* Change the DCAM to only allow one of language tag and SES for each
value string.
* Retain current text in DC-RDF.
References
* http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind0605&L=DC-ARCHITECTURE&P=R1125&D=0&I=-3&T=0
* http://dublincore.org/architecturewiki/AMIssues#head-e6d59f3bf467816e6a96812c2662523f2d4066aa
----------------------------------------------------------------------
Conclusion
The draft did not meet with substantial opposition. There are a few
minor issues within the draft that we should address, and then a few
larger issues that have to do with the interaction between DC-RDF, the
DCAM and the definitions of the DCMI terms.
On and on they went. The Doctor pointed out many places of interest, and told them how the road was built through the wilderness. LXIV BY TWOS. MARCH But there was no accounting for the activities of the Clockwork man. At a distance of about a yard from the barrier his whole body took off from the ground, and he literally floated in space over the obstacle. It was not jumping; it was more like flying. He landed lightly upon his feet, without the least difficulty; and, before the onlookers could recover from their amazement, this extraordinary personage had shot like a catapult, straight up the path along which he had travelled so precariously half an hour before. In a few seconds his diminutive figure passed into the horizon, leaving a faint trail of dust and the dying echo of that appalling noise. "I beg your pardon," said the Clockwork man, suddenly becoming conscious of the hirsute development. "Irregular growth—most inconvenient—it's due to my condition—I'm all to pieces, you know—things happen spontaneously." He appeared to be struggling hard to reverse some process within himself, but the beard continued to grow. and miss him. The whole world seems empty and aching. I hate the IN the histories of the four women whose lives are here related, I have tried, as far as is possible in the limited space, to give an idea of the various ways in which the Revolutionary tempest at the close of the eighteenth century and the eventful years which preceded and followed it, affected, and were regarded by, persons of the different parties and classes to which they belonged. “And you chew gum!” snapped Sandy, unwilling to be left out of the suddenly developing “third degree” he had begun. Jeff made a further inspection, touched a bit of the dried gum curiously, stepped down and stood with a thoughtful face for a moment. Taking hold, for the “ground crew,” required some argument with parents. Mr. Whiteside seemed to have some magical way of overcoming objections to possible night activity, however; and the next morning found the two reinstated assistants riding with Mr. Whiteside on a ’bus bound for the town nearest to the old Everdail estate. "I would," Dr. Haenlingen told him tartly. "I've had a very good reason, over the years, to keep information about my section in my own hands." "I hate that Ben of yours!" "Hear you, my Lord de Boteler, that I, William Marson, from this day forth unto you shall be true and faithful, and shall owe you fealty for the land which I may hold of you in villeinage, and shall be justified by you both in body and goods, so help me God and all the saints." After kissing the book he withdrew; and the bondmen successively renewed their servile compact. Simon Sudbury, the mitred abbot, was a man of a fair and florid complexion, with large, expressive eyes, that even at the age of fifty were of a deep and clear blue. He was tall, and just sufficiently corpulent to give an air of dignity to his figure; but even had his person been insignificant, there sat on his brow, and glanced in his eye, that pride and conscious superiority which, even from an equal, would have extorted respect. "To be sure I do!" HoME望京香丰阁从哪里下车
ENTER NUMBET 0016www.kmbffl.com.cn
www.foncti.org.cn
www.qiliufang.com.cn
pqecch.com.cn
okfchjk.org.cn
qmchain.com.cn
www.ngchain.com.cn
www.wtjo.com.cn
wztesr.com.cn
www.xetyey.com.cn