# File nqxml/tokenizer.rb, line 104
 def replaceParamRefs(str)
	    return nil if str.nil?
	    copy = str.dup
	    replacement = ''
	    while copy =~ /%([^%;]*);/mn
		replacement << $`
		ref = $&
		refName = $1
		copy = $'
		val = @paramEntities[refName]
		if val.nil?
		    str = "entity reference '#{ref}' is undefined"
		    raise ParserError.new(str, self)
		end
		val = replaceParamRefs(val)
		replacement << val
	    end
	    replacement << copy
	    return replacement
	end