The XHTML 1.0 DTD - HTML and XHTML: The Definitive Guide - page 1062

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<!ELEMENT h2 %Inline;>
<!ATTLIST h2
%attrs;
%TextAlign;
>
<!ELEMENT h3 %Inline;>
<!ATTLIST h3
%attrs;
%TextAlign;
>
<!ELEMENT h4 %Inline;>
<!ATTLIST h4
%attrs;
%TextAlign;
>
<!ELEMENT h5 %Inline;>
<!ATTLIST h5
%attrs;
%TextAlign;
>
<!ELEMENT h6 %Inline;>
<!ATTLIST h6
%attrs;
%TextAlign;
>
<!--=================== Lists ============================================-->
<!-- Unordered list bullet styles -->
<!ENTITY % ULStyle "(disc|square|circle)">
<!-- Unordered list -->
<!ELEMENT ul (li)+>
<!ATTLIST ul
%attrs;
type %ULStyle; #IMPLIED
compact (compact) #IMPLIED
>
<!-- Ordered list numbering style
1 arabic numbers 1, 2, 3, ...
a lower alpha a, b, c, ...