Entity References

Some characters have a special meaning in XML.

If you place a character like "<" inside an XML element, it will generate an error because the parser interprets it as the start of a new element.

This will generate an XML error:
<message>if salary < 1000 then</message>

To avoid this error, replace the "<" character with an entity reference:
<message>if salary &lt; 1000 then</message>

There are 5 predefined entity references in XML:
&lt; < less than
&gt; > greater than
&amp; & ampersand
&apos; ' apostrophe
&quot; " quotation mark

Note: Only the characters "<" and "&" are strictly illegal in XML. The greater than character is legal, but it is a good habit to replace it.