/*Entity is a group of words which print a special symbol.
Like if we want to show copy right symbol in html page then we use © code and browser convert this to actual copyright symbol.
There have lots of entity, you can find them all form http://dev.w3.org/html5/html-author/charref
if you want to use < or > or both <> into a node value than xml will give and warning or make this value as a node.
So tell the xml parser that < or > is not tag symbol it is a entity.To do that you have to right <(<) and >(>) instead of < and > symbol.
Entity references always begin with an ampersand (&) and end with a semicolon (;).
DO not need to use & and ; symbol begin and end of entity.Remove it when you want to use it to DOMDocument::createEntityReference
Then append to to a tag where you want to show this symbol.Like below
$example=$dom->createElement("example","This is copyright ");
This is copyright ©