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Schema.org properties defined mutiple times in the canonical RDFa specification

From: Simon Spero <sesuncedu@gmail.com>
Date: Sat, 17 May 2014 20:05:23 -0400
Message-ID: <CADE8KM4C1gNfSnAiHYwS5pO3=iQ6Oek7Azpv9c4XZDdmoXZvng@mail.gmail.com>
To: W3C Web Schemas Task Force <public-vocabs@w3.org>
Several properties are multiply defined in "[t]he canonical machine
representation of schema.org", located at
schema_org_rdfa.html<http://schema.org/docs/schema_org_rdfa.html>
 .

Methodology:
Statements were processed using Sesame 2.7.11, with the Semargl-RDFa 0.6.1
parser.

A property was considered to be multiply defined if more than one
*different* rdfs:comment property was specified for the Resource.

*Results: *

Nine properties were defined more than once;  one property (startTime) was
defined thrice.  These can be quartered into three halves*.

*Group 1: Failure to remove superseded definitions*

 Most multiple definitions reflect an extended redefinition of a property
with a failure to remove the superseded definition. This is usually
reflected in the comment, and in domain and range inclusions in the later
definition that repeat those in the prior definition:

*1: http://schema.org/issuedBy <http://schema.org/issuedBy>*

http://schema.org/issuedBy
"The organization issuing the permit."
"The organization issuing the ticket or permit."

*2: http://schema.org/provider <http://schema.org/provider>*

http://schema.org/provider
"The organization or agency that is providing the service."
"The person or organization providing the service, reservation, or creative
work."

*3: http://schema.org/priceCurrency <http://schema.org/priceCurrency>*

http://schema.org/priceCurrency
"The currency (in 3-letter ISO 4217 format) of the offer price or a price
component, when attached to PriceSpecification and its subtypes."
"The currency (in 3-letter ISO 4217 format) of the price or a price
component, when attached to PriceSpecification and its subtypes."


*4: http://schema.org/startTime <http://schema.org/startTime>*

http://schema.org/startTime
"When the Action was performed: start time. This is for actions that span a
period of time. e.g. John wrote a book from *January* to December."
"The time a FoodEstablishmentReservation is required to end."
"When a FoodEstablishmentReservation starts or an Action was performed:
start time. This is for actions that span a period of time. e.g. John wrote
a book from *January* to December."


*Group 2:  Different properties given the same name. *

More problematic cases appear to reflect different properties that have
accidentally been given the same name.

*5: http://schema.org/carrier <http://schema.org/carrier>*

http://schema.org/carrier
"The party responsible for the parcel delivery."
"The airline designated as the carrier for the flight."

*6: http://schema.org/member <http://schema.org/member>*

http://schema.org/member
"A member of this organization."
"The individual with the membership."

*Group 3:  Properties that are hard to classify.*

A few cases are confusing or problematic in other ways:

*7: http://schema.org/acceptsReservations
<http://schema.org/acceptsReservations>*

http://schema.org/acceptsReservations
"Either <code>Yes/No</code>, or a URL at which reservations can be made."
"Does the establishment accept reservations?"

The rangeInclusions for the first definition are schema:Text and schema:URL
The rangeInclusion for the second definition is schema:Boolean.

schema:Boolean is a subclass of schema:DataType, which is generally
corresponds to literal values. There are comments on
schema:requiresSubscription that suggest that the lexical space is "true"
or false, noting that an older version of the comment on that  property
said "yes/no".
There are also two defined instances of Boolean: http://schema.org/True and
http://schema.org/False. These have the same lexical form as URLs.
Non property and class instances in the schema.org schema is generally
reserved for schema:Enumeration types.



*8: http://schema.org/maxValue <http://schema.org/maxValue>*

http://schema.org/maxValue
"The upper of the product characteristic."
"Specifies a regular expression for testing literal values according to the
HTML spec."


*9: http://schema.org/minValue <http://schema.org/minValue>*

http://schema.org/minValue
"The lower value of the product characteristic."
"Specifies a regular expression for testing literal values according to the
HTML spec."

All  definitions for 8 and 9 have the same range (schema:Number).

The second definition in each pair refers to the HTML spec.  It seems quite
unlikely that the reference to regular expression was intended, as the
comment appears to be duplicated from schema:valuePattern (which oddly,
also only has the range schema:Number).

Because of the context in which the second definitions of minValue and
maxValue are specified, it appears that they are intended to correspond to
the HTML5  input attributes min and max, which need not be numbers (but
need to be coercible to numbers).

 This doesn't make too big a difference, since propertyValueSpecification
does not provide any place to specify the value type, (and it's with HTML5
it's always possible to declare your own Fork).

The descriptive text next to the definition of minValue and maxValue on the
web page at
http://schema.org/PropertyValueSpecification suggests that the system
backing schema.org is not intended to support multiple definitions of the
kind noted in this message.

PropertyExpected TypeDescriptionProperties from
PropertyValueSpecification<http://schema.org/PropertyValueSpecification>
defaultValue <http://schema.org/defaultValue>

Thing <http://schema.org/Thing>
orLiteral <http://schema.org/Literal> The default value of the input. For
properties that expect a literal, the default is a literal value, for
properties that expect an object, it's an ID reference to one of the
current values.maxValue
<http://schema.org/maxValue>Number<http://schema.org/Number>
 The upper of the product characteristic.minValue<http://schema.org/minValue>
Number <http://schema.org/Number> The lower value of the product
characteristic.

[Joe Biden adds that there is figuratively no such type as
http://schema.org/Literal ]
Received on Sunday, 18 May 2014 00:05:52 UTC

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