self axis vs .

Andrew Welch started a nice discussion about comparison of XPath's self axis vs ., on xsl-list.

Andrew wrote that he has seen people writing self::elem//whatever instead of .//whatever.

I looked at the XPath 2.0 spec to find the relevant definitions. Below are the definitions from the XPath 2.0 spec.

<quote>
the self axis contains just the context node itself

. is known as, "context item expression".
A context item expression evaluates to the context item, which may be either a node (as in the expression fn:doc("bib.xml")/books/book[fn:count(./author)>1]) or an atomic value (as in the expression (1 to 100)[. mod 5 eq 0]).

The context item is the item currently being processed. An item is either an atomic value or a node. When the context item is a node, it can also be referred to as the context node.
</quote>

Wendell Piez wrote,

It also works to test whether the current node is actually an 'elem' when you process it or traverse from it.

Mukul: I personally prefer the style, .//whatever as it is shorter. But I think, there are important use cases for using the self:: axis.

Like for e.g.,

<xsl:template match="*[not(self::elem)]">
  <!-- do something -->
</xsl:template>


<xsl:template match="*">
  <xsl:if test="not(self::elem)">
    <!-- do something -->
  </xsl:if>
</xsl:template>

Vyacheslav Sedov wrote,

In XSLT 2.0 I prefer to use "* except elem".