Javadoc
Reference to a block, a structured part of the content of a document or an object property.
While other references are generally unique, defined application wide, and usable to reach their target instance,
the meaning of block references depends on their usage, may not be unique and are not necessarily a way to reach
the referenced instance. We may have different kind of block references, for different purposes (for example
identifying a header in the content, linking signature to macro block, etc...).