The information is then kept in another file. External entities allow an XML document to refer to an external file. External entities contain either text or binary data. If they contain text, the content of the external file is inserted at the point of reference and parsed as part of the referring document. Binary data is not parsed and may only be referenced in an attribute.
Binary data is used to reference figures and other non-XML content in the document.
The entity declaration in this example refers to documents that are located in different sections. They are placed into the XML file by using the entities, rather than cutting and pasting the contents of separate files together. In this case, the XML processor will parse the content of that file as if its content had been typed at the location of the entity reference. The entity is also an external entity, but its content is binary. You may not reference an external entity from within element attributes.