Locates one or more entities as anchors
Used to locate one or more entities, through entity declarations. The content of this element must be the name(s) of the entity declaration(s) for the entity. Names are separated with a comma or blanks. The entity must be declared in the same instance as this element, or in module named in attribute 'docorsub'.
For further explanations, see the HyTime standard (ISO 10744), clause 8.3.2.2.