Noob: where can i find a list of operators and methods i can use in XSL?

Hi again,

After my last post i was thinking where i could find 
a list of operators and methods i can use in XSL

Like this if statement and the operator "not"
<xsl:if test='not(. = "null")'><xsl:value-of select='.'/></xsl:if>

btw: My background is more php/flash actionscript


 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list