Every point is either between two nodes or between two characters in the parsed character data of a document. To make sense of this you have to remember that parsed character data is part of a text node. For instance, consider this very simple but well-formed XML document:
<GREETING>
Hello
</GREETING>
There are exactly three nodes and 13 distinct points in this document. In order the points are:
The point before the root node
The point before the GREETING element node
The point before the text node containing the text "Hello" (as well as assorted white space)
The point before the white space between <GREETING> and Hello.
The point before the first H in Hello
The point between the H and the e in Hello
The point between the e and the l in Hello
The point between the l and the l in Hello
The point between the l and the o in Hello
The point after the o in Hello
The point after the white space between Hello and </GREETING>.
The point after the GREETING element.
The point after the root node.
The exact details of the white space in the document are not considered here. XPointer collapses all runs of white space to a single space.