Adding Header Declaration
<!-- Parameter entity declarations for later use: --> <!ENTITY % common-elements "list | image | quote | anchor"> <!ENTITY % a.global ”ID ID #IMPLIED">
<!-- Header information: --> <!ELEMENT header (sender+, recipient+, date, main-heading, subject*)> <!ATTLIST header %a.global;> <!ELEMENT sender (#PCDATA)> <!ELEMENT recipient (#PCDATA)> <!ATTLIST recipient %a.global;> <!ELEMENT date (#PCDATA)> <!ATTLIST date %a.global; SORTFORM CDATA #IMPLIED> <!ELEMENT main-heading (#PCDATA)> <!ELEMENT subject (#PCDATA)>