XML Parsers and how they handle internal entities (amp, quote, apos, etc...)

Hi,

I have a small question here... when an XML parser parses a document, doest
it have to expand internal entities like ' &quote; < > and &?
I am asking this question because expat seems to expand ' and &quote;
but not & and it is causing me some trouble. Is this a normal behavior?

Thanks in advance!
Daniel Shane