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GoodRelations - The Web Vocabulary for E-Commerce

This is the archive of the goodrelations dicussion list

GoodRelations is a standardized vocabulary for product, price, and company data that can (1) be embedded into existing static and dynamic Web pages and that (2) can be processed by other computers. This increases the visibility of your products and services in the latest generation of search engines, recommender systems, and other novel applications.

[goodrelations] gr:hasUnitOfMeasurement in a gr:UnitPriceSpecification

Martin Hepp (UniBW) martin.hepp at ebusiness-unibw.org
Thu Jan 28 11:18:30 CET 2010

Dear all:

This question may be relevant for a broader audience:
> I think I don't understand the usage of gr:hasUnitOfMeasurement in a 
> UnitPriceSpecification in general.
> If somebody is not sure whether the offering is a bundle (or if the 
> UnitPriceSpecification of a product can meaninfully refer to a "unit 
> or piece"),
> is it wrong to add the property "gr:hasUnitOfMeasurement" with the 
> value "C62"?
> Would it be better to add this property with C62 or ignore this 
> property completely?
> I only found one example in our wiki where the value of 
> hasUnitOfMeasurement is not C62 at
> http://www.ebusiness-unibw.org/wiki/GoodRelationsRental
Note that the Unit of Measurement is relevant in two aspects of an offer:
- First, it can be used to specify the quantities of individual 
components of a bundle.
- Second, it can be used to indicate the unit to which a price 
specification refers.


For a simple offer, you could say that you offer to sell 200 grams of 
salami and that the price was 20 euros per kilogram of salami. Then, the 
gr:UnitOfMeasurement attached to the gr:TypeAndQuantityNode is "grams" 
(GRM in UN/CEFACT) and the gr:UnitOfMeasurement attached to the 
gr:UnitPriceSpecification is "kilogram" (KGM in UN/CEFACT).

As soon as there is more than one component included in the offer, the 
only meaningful unit of measurement for the price specification is "C62" 
for unit or piece.


If you offer 200 grams of salami and 1 liter of beer for altogether 8 
euros, then you would use "GRM" and "LTR" for the two 
gr:TypeAndQuantityNode instances and "C62" for the unit price 

There can be rare cases of bundles that allow other units of measurement 
for the price specification, but as a rule of thumb, use C62 as soon as 
there is more than one component included the offer.

Relevant exceptions can be found for business functions other than 
gr:Sell - e.g. Rental: If you offer to rent out a pair of skis and 2 
tons of snow, then the price may be specified per hour (HUR in 
UN/CEFACT). But again, those cases are rare (yet still perfectly 
supported by GoodRelations).

Best wishes

Martin Hepp

martin hepp
e-business & web science research group
universitaet der bundeswehr muenchen

e-mail:  hepp at ebusiness-unibw.org
phone:   +49-(0)89-6004-4217
fax:     +49-(0)89-6004-4620
www:     http://www.unibw.de/ebusiness/ (group)
         http://www.heppnetz.de/ (personal)
skype:   mfhepp 
twitter: mfhepp

Check out GoodRelations for E-Commerce on the Web of Linked Data!

Project page:

Resources for developers:

Overview - http://www.heppnetz.de/projects/goodrelations/webcast/
How-to   - http://vimeo.com/7583816

Recipe for Yahoo SearchMonkey:

Talk at the Semantic Technology Conference 2009: 
"Semantic Web-based E-Commerce: The GoodRelations Ontology"

Overview article on Semantic Universe:

Tutorial materials:
ISWC 2009 Tutorial: The Web of Data for E-Commerce in Brief: A Hands-on Introduction to the GoodRelations Ontology, RDFa, and Yahoo! SearchMonkey 

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