The & in the XML file appears??

These days in cooperation with a company project, the other side provides the RSS interface, through this interface, in our website, but the other side of the RSS appeared some trouble characters, such as &,®,& #8482; Wait These characters are placed in XML, and if you do not do special processing, there will be errors. For example, the following XML:
<item>&</item>
Parsing this fragment in IE, and some parsing DOM, creates an error.
In the technical specification of the consortium, you can also see that such a character is not allowed to occur:
http://www.w3.org/TR/2001/REC-xml-c14n-20010315
For example: The characters allowed for Text Nodes are as follows: The string value, except all ampersands are replaced by &amp;, all open angle brackets (&L T are replaced by &AMP;LT;, all closing angle brackets (>) are replaced by &gt;, and all #xD characters are Replac Ed by & #xD;.
Because of the number of these special characters and the amount of work we replace in the XML, we can define them in the DTD file:
For example, add the following sections to the DTD file:
<!--PERCENT SIGN-->
<! ENTITY amp "& #38; #38;" >
<!--COPYRIGHT SIGN-->
<! ENTITY reg "& #x00AE;" >
<!--REG TRADE MARK SIGN-->
<! ENTITY trade "& #x2122;" >
and defining this XML file in XML requires this DTD support:
<! DOCTYPE headcount SYSTEM "EULA.DTD" >
This appears in the XML file & &reg; & #8482; Such special characters will no longer be an error.