Figure 1. External entity in the Editing Window and ContentMap.
Convert a part of document content to an external entity
You can convert any part of document content to a reference to a newly-declared external entity.
Inserting Declared External Entity
You can insert a reference to an external entity which is declared in the current document.
Inserting External Entity from File
You can insert a reference to an external entity which is not yet declared in the current document.
Convert an external entity to a regular content
You can convert an external entity reference to a regular content.