Common Schema.org Properties for Connecting and Disambiguating Data Items

At Schema App we value making structured data as specific as possible. Below are descriptions of common properties and practices used by Schema App to disambiguate schema markup.

TABLE OF CONTENTS

• about
• additionalType
• mainEntityOfPage
• mainEntity
• mentions
• sameAs
• url
• @id

about

The about property is used to express the subject matter of something (usually a CreativeWork). Because it is possible for a piece of content to be "about" more than one entity, this property can be used multiple times to reference key entities. If you're linking to an external authority, like Wikipedia or Wikidata, note you will want to create a Data Item for the entity you're describing, and nest the URL under the sameAs property.

additionalType

The additionalType property is used to add more specific types from external vocabularies or authorities like Wikipedia or Wikidata. These should be in the form of URLs. For more information, see our article, How to use the additionalType and sameAs properties.

mainEntityOfPage

The mainEntityOfPage property is used to explicitly express the relationship between a page and its primary entity. The inverse of this property is "mainEntity". If several entities are referenced on a particular page, this property clarifies the main one. An entity can be the mainEntityOfPage for more than one URL (e.g a Product can be the subject of multiple pages) but by definition, a page can only have one mainEntity. 

mainEntity

The mainEntity property is available on all subtypes of CreativeWork to say that the CreativeWork is primarily about a particular entity. A CreativeWork should only have one "mainEntity". The inverse of this property is "mainEntityOfPage".

mentions

The mentions property is similar to about in that it can refer to multiple entities or topics. In contrast to the "about" property, "mentions" is more appropriate for calling out entities or topics that are referenced but not explored in depth. For example, a MedicalWebPage may be about a MedicalCondition, but it may also mention other related conditions without going into as much detail.

sameAs

The sameAs property relates a thing (data item) to a URL that indirectly identifies it. It's most commonly used to link Organizations and Businesses to their social media sites. It's also useful for linking data items to authorities like Wikipedia or Wikidata. Note that sameAs should only be used to express that an entity is exactly the same as an entity from another source. For more information, see our article, How to use the additionalType and sameAs properties.

url

The url property should be reserved to refer to more official or authoritative web pages, such as the item’s official location on a website. For example, the URL of an Organization data item would be the homepage of the website about that Organization. 

@id

While not a property in Schema.org, @id is used in JSON-LD to uniquely identify things (or data items) described in a document. Schema App automatically generates @ids for each data item you create so that they can be unambiguously identified and referenced by other data items in your schema markup graph.