The ConstraintNode type is provided to support usecases in which a node in a structured data graph is described with properties which appear to describe a single entity, but are being used in a situation where they serve a more abstract purpose. A [ConstraintNode](https://schema.org/ConstraintNode) can be described using [constraintProperty](https://schema.org/constraintProperty) and [numConstraints](https://schema.org/numConstraints). These constraint properties can serve a variety of purposes, and their values may sometimes be understood to indicate sets of possible values rather than single, exact and specific values.
