XML's DTD not enforcing order of objects

This is the DTD

<!-- Root element article should contain the elements in parenthesis in that order. -->
<!ELEMENT article (headline,description,authorid,pubdate,status,keywords,body)>

<!-- CDATA stands for Character Data, this attribute can contain any string of characters or numbers. -->
<!ATTLIST article

<!-- // PCDATA stands for Parsed Character Data. Element must contain only text. -->
<!ELEMENT headline (#PCDATA)>
<!ELEMENT description (#PCDATA)>
<!ELEMENT authorid (#PCDATA)>
<!ELEMENT pubdate (#PCDATA)>
<!ELEMENT status (#PCDATA)>
<!ELEMENT keywords (#PCDATA)>

This is the XML file:

<?xml version="1.0" standalone="no" ?>
	<headline id="somenumber">
	<description>This article is to practice creation of a CMS-powered website</description>
	<keywords>keywords separated by spaces</keywords>
		<h1>this is a heading</h1>

According to the book Im reading (No nonsense XML Web Development with PHP in page 62) it says:

the sequence not only specifies the order in which the elements should appear, but also, how many of each element should appear

So, to make sure my DTD was working, I put the elements in the WRONG order but there was NO error message. I tested with IE and FF.

Do DTDs specify the ORDER in which elements should appear?

Thanks in advance,