<!-- QUESTIONMARK matches one character except "/" -->
<!ELEMENT TokenList (CONST|STAR|TWOSTARS|SLASH|QUESTIONMARK)+>
-<!ELEMENT Prefix (#PCDATA)>
+<!ELEMENT Prefix (CONST|STAR)>
<!-- XPointers have max depth = 2 (see CIC inductive definitions) -->
-<!ELEMENT FragmentID ((NUMBER|STAR), (NUMBER|STAR)?)>
+<!ELEMENT FragmentID (NUMBER|TWOSTARS|STAR)+>
<!-- MathQL boolean expressions -->