In general, the prefix
and typeof
HTML attributes are so-called RDFa attributes: these are used to specify the semantics of HTML elements (which themselves tend to be more formatting-oriented).
More specifically: these attributes allow you to map HTML elements to semantic types or properties which are defined in a public Vocabulary (such as Schema.org).
In your case, they are referring to the Vocabulary with URI http://www.sdl.com/web/schemas/core
. This is not a public Vocabulary, but used internally by DXA to do semantic mapping to CM Schemas. It does not make sense to use this as a public Vocabulary.
The reason why this happens is because your View Models have a SemanticEntity
annotation that declares the "SDL Core" vocabulary as Public. I see people doing that a lot, but it does not make sense.