Updated descriptions for Offer and AggregateOffer (#2375)

data/schema.rdfa

@@ -164,14 +164,14 @@
 
     <div typeof="rdfs:Class" resource="http://schema.org/Offer">
       <span class="h" property="rdfs:label">Offer</span>
-      <span property="rdfs:comment">An offer to transfer some rights to an item or to provide a service — for example, an offer to sell tickets to an event, to rent the DVD of a movie, to stream a TV show over the internet, to repair a motorcycle, or to loan a book.\n\nFor [GTIN](http://www.gs1.org/barcodes/technical/idkeys/gtin)-related fields, see [Check Digit calculator](http://www.gs1.org/barcodes/support/check_digit_calculator) and [validation guide](http://www.gs1us.org/resources/standards/gtin-validation-guide) from [GS1](http://www.gs1.org/).</span>
+      <span property="rdfs:comment">An offer to transfer some rights to an item or to provide a service — for example, an offer to sell tickets to an event, to rent the DVD of a movie, to stream a TV show over the internet, to repair a motorcycle, or to loan a book.\n\nNote: As the [[businessFunction]] property, which identifies the form of offer (e.g. sell, lease, repair, dispose), defaults to http://purl.org/goodrelations/v1#Sell; an Offer without a defined businessFunction value can be assumed to be an offer to sell.\n\nFor [GTIN](http://www.gs1.org/barcodes/technical/idkeys/gtin)-related fields, see [Check Digit calculator](http://www.gs1.org/barcodes/support/check_digit_calculator) and [validation guide](http://www.gs1us.org/resources/standards/gtin-validation-guide) from [GS1](http://www.gs1.org/).</span>
        <span>Subclass of: <a property="rdfs:subClassOf" href="http://schema.org/Intangible">Intangible</a></span>
        <span>Source:  <a property="dc:source" href="http://www.w3.org/wiki/WebSchemas/SchemaDotOrgSources#source_GoodRelationsTerms">GoodRelationsProperties</a></span>
     </div>
 
     <div typeof="rdfs:Class" resource="http://schema.org/AggregateOffer">
       <span class="h" property="rdfs:label">AggregateOffer</span>
-      <span property="rdfs:comment">When a single product is associated with multiple offers (for example, the same pair of shoes is offered by different merchants), then AggregateOffer can be used.</span>
+      <span property="rdfs:comment">When a single product is associated with multiple offers (for example, the same pair of shoes is offered by different merchants), then AggregateOffer can be used.\n\nNote: AggregateOffers are normally expected to associate multiple offers that all share the same defined [[businessFunction]] value, or default to http://purl.org/goodrelations/v1#Sell if businessFunction is not explicitly defined.</span>
        <span>Subclass of: <a property="rdfs:subClassOf" href="http://schema.org/Offer">Offer</a></span>
     </div>