Entities |
An XML entity can best be understood as a macro replacement facility, in which the replacement can be either parsed (the text becomes part of the XML document) or unparsed. If unparsed, the entity declaration points to external binary data that cannot be parsed. Additionally, the replacement text for parsed entities can come from a string or the contents of an external file. During parsing, a parsed entity reference is replaced by the substitution text that is specified in the entity declaration. The replacement text is then reparsed until no more entity or character references remain.

To simplify document parsing, two distinct types of entities are used in different situations: general and parameter. The basic syntax for referencing both entity types is almost identical, but specific rules apply to where each type can be used.