Note: There is a newer version of this specification see VEC 2.0.1
A UsageConstraintSpecification is intended to describe the allowed usage of the constrainedParts.
A UsageConstraintSpecification is a container for various UsageConstraints each representing a single constraint. The sequencing of the UsageConstraints specifies the priority: a general denial may be relativized by a following UsageConstraint and vice-versa. The relationships UsageConstraint.usageNode and UsageConstraint.project make it possible to specify at which UsageNodes respectively in which Projects the regarded PartVersions are allowed / denied to be used.