Resource description framework property
Use RDFa shorthand notation to assign a machine-readable RDFa property to a phrase to extend its semantic meaning beyond HTML.
RDFa shorthand assigns a "property" attribute to a phrase. The syntax is a question-mark ? immediately followed by a semantic property chosen from a defined RDFa vocabulary. See https://schema.org for a list of community maintained vocabularies.
Each phrase may have only one RDFa attribute.
Shorthand attributes should be placed between a phrase's semantax and its textual composition. Shorthand attributes may optionally be preceded by one or more spaces. At least one space must be used after the last shorthand attribute, before the beginning of the textual composition.
A phrase may have any combination of shorthand attributes (#, ., *, ^, `, +, ? ) and they may specified in any order.
Here is what an RDFa attribute looks like within the body of a manuscript.