There are two additional ways in XML documents to reference characters:
a numeric character reference refers to a character an entity reference refers to a series of characters Where entities are used, the referenced characters appear. Numeric character references: A numeric character reference can be specified in two formats: nnnn; or hhhh; where the n decimal digits or the h hexadecimal characters identify the Unicode character code of the referenced character. Entity references: An entity reference is an alternative name for a series of characters. You can use an entity in the &name; format, where name is the name of the entity. There are some predefined entities in XML, furthermore you can declare entities in a DTD (Document Type Definition). Predefined entities: The following predefined entities exist in XML: Entity name Character Decimal reference Hexadecimal reference quot " " " amp & & & apos ' ' ' lt < < < gt > > > Declaring entities: You can declare entities in a DTD in the following format: where name is the name of the entity and text is the referenced text that appears where the entity is used.