xpath - Self axis in xslt -

<element>   <bye>do not delete me</bye>   <hello>do not delete me</hello>   <hello>delete me</hello>   <hello>delete me</hello> </element> 

applied above xml, deletes nodes except first hello child of /element:

<xsl:template match="hello[not(current() = parent::element/hello[1])]" /> 

why these ones doesn't work? (assuming first node not text node)

<xsl:template match="hello[not(self::hello/position() = 1)]" /> <xsl:template match="hello[not(./position() = 1)]" /> 

or one?

<xsl:template match="hello[not(self::hello[1])]" /> 

what self axis selecting? why isn't last example equivalent not(hello[1])?

first, wrong when that:

this deletes nodes except first hello child of /element

the truth deletes (if that's correct word) hello child of /element value not same value of first 1 of these. example, given:

xml

<element>     <hello>a</hello>     <hello>b</hello>     <hello>c</hello>     <hello>a</hello> </element> 

the template:

<xsl:template match="hello[not(current() = parent::element/hello[1])]" /> 

will match second , third hello nodes - not first or fourth.

now, regard question: in xslt 1.0, position() not valid location step - this:

<xsl:template match="hello[not(self::hello/position() = 1)]" /> 

should return error.

in xslt 2.0, pattern hello[not(self::hello/position() = 1)] not match any hello element - because there 1 node on self axis, , therefore position 1.

similarly:

<xsl:template match="hello[not(./position() = 1)]" /> 

is invalid in xslt 1.0.

in xslt 2.0, ./position() return 1 same reason before: . short self::node() , there 1 such node.

finally, template:

<xsl:template match="hello[not(self::hello[1])]" /> 

is looking node doesn't have (the first instance of) itself. of course, no such node can exist.