Locates two SGML elements, by their ID attribute values. The first ID is the span start element (the first element in the span), the second is the span end element (the last one in the span).
Used when a span is located. The content of this element must be identical to the values of the located elements' ID-attributes. Exactly two ID's are required as content. The ID's are separated with a comma or blanks.
The module in which the span occurs is identified in attribute "docorsub", pointing at an entity declaration in the same instance as this element.
For further explanations, see the HyTime standard (ISO 10744), clause 8.3.2.2.