Entity Replacement

hi.. can some one please explain this to me? im not clear what its actually means.... thx for helping~~~

doc = Document.new('<!DOCTYPE         foo [ <!ENTITY ent "replace"> ]><a>replace         &ent;</a>',{:raw=>:all})         doc.root.text #-> "replace &ent;" doc.to_s # Generates: #         <!DOCTYPE foo [ # <!ENTITY ent "replace"> #         ]><a>replace &ent;</a>

and shud i place it in the xml file or ...other places?

cheers