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 [ ]>replace
&ent;
’,{:raw=>:all})
doc.root.text #-> “replace &ent;” doc.to_s # Generates: #
<!DOCTYPE foo [ # #
]>replace &ent;

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

cheers