XPointer fragment identifiers

An XPointer fragment identifier (the substring to the right of # in the URI) is either

the value of some ID attribute in the document (ID attributes are specified by the DTD or DSD),
a sequence of element numbers denoting the path from the root to an element (e.g. /1/27/3), or
a sequence of the form
xpointer(...) xpointer(...) ...
containing a list (typically of length 1) of XPointer expressions.
Each expression is evaluated in turn, and the first where evaluation succeeds is used. (This allows alternative pointers to be specified thereby increasing robustness.)

(XPointer allows for other means of specifying pointers - XPointer pointers are recognized by "xpointer(...)".)

Next: We will now dig into XPath and then later describe what additional features XPointer adds to XPath...