The following detail the changes made to the DTD in the 2001-06-01 DTD update. See also the change log.
The symbol element has been given extra attributes. This is to reduce the dependency on lookup tables when processing entities in in-house XSL stylesheets etc.
price added as a subelement to bindinggroup
name content model changed from
<!ELEMENT name ((%nameelements;), alternativename*)>
to
<!ELEMENT name (%nameelements; | alternativename)+>
to allow author/affiliation links to appear after the alternative name. For an expanded explanation of alternative name tagging, see alternativename.