Changelog/20100916

=Changelog: Service Update September 16, 2010=

Summary: This service update was mainly for Google with the goal of simplifying markup as much as possible. In particular, we improved the use of gr:Offering and made changes that make RDFa markup patterns shorter


 * 1) Added gr:condition property
 * 2) Changed the range of gr:includes to gr:ProductOrService, which allows much more concise markup in the general case of linking an offer of a single product to model data. Also updated the inference rules for expanding the shortcut (if the object of the triple is a gr:ProductOrServiceModel, one must create both gr:TypeAndQuantityNode and gr:ProductOrServicesSomeInstancesPlaceholder instances)
 * 3) Changed the domain of gr:serialNumber to the union of gr:Offering and gr:ActualProductOrServiceInstance
 * 4) Changed the domain of gr:hasInventoryLevel to the union of gr:Offering and gr:ProductOrServicesSomeInstancesPlaceholder
 * 5) Added a gr:category property for attaching product category information in a lightweight manner if no dedicated ontology exists
 * 6) Added a gr:name property as a shortcut for dc:title and rdfs:label
 * 7) Added/reactivated the gr:description property as a shortcut for rdfs:comment and dcterms:description. Also changed the domain to owl:Thing
 * 8) Defined the product features gr:weight, gr:width, gr:height, gr:depth, and gr:color directly in GoodRelations
 * 9) Added the range rdfs:Literal to gr:hasMinValue and gr:hasMaxValue so that they become fully usable for annotations (not just for queries, as originally).
 * 10) Changed the cardinality recommendation for gr:hasMinValue and gr:hasMaxValue to 0..1 and updated their textual definition.
 * 11) Added a gr:hasValue property, an rdfs:subPropertyOf of gr:hasMinValue and gr:hasMaxValue, which simplifies the markup for quantitative data without breaking existing content
 * 12) Added the range rdfs:Literal to all text properties, i.e. gr:condition, gr:description, gr:legalName, and gr:category
 * 13) Removed unused namespace declarations xmlns:swrl="http://www.w3.org/2003/11/swrl#" and xmlns:swrlb="http://www.w3.org/2003/11/swrlb#"
 * 14) Added UN/CEFACT unit recommendations to gr:weight, gr:width, gr:height, and gr:depth
 * 15) Updated the intro section: Removed gr:ActualProductOrServiceInstance and gr:ProductOrServicesSomeInstancesPlaceholder from the list of core classes, since they will be less important for very popular cases
 * 16) Updated the UML class diagram accordingly
 * 17) Added rdfs:isDefinedBy to all new elements
 * 18) Fixed the rdfs:comment of gr:QualitativeValue
 * 19) Polished the text of the ontology meta-data
 * 20) Fixed the text of gr:BusinessEntity to make clear it can also be used with gr:seeks and that stores are gr:LocationOfSalesAndServiceProvisioning
 * 21) Polished the text of gr:BusinessFunction
 * 22) Updated the text of gr:Offering to reflect the new gr:includes shortcut to model data
 * 23) Polished the text for gr:ProductOrService