> by the way  - in my case i began use select="if () then () else ()"
> structure - look like it work as expected, i am not fan of 
> several-lines long attributes but at least it work

You can certainly use the xsl:choose coding style if you prefer, but get
into the habit of using the "as" attribute on xsl:variable, as Andrew
suggested, otherwise you will be creating a new temporary document when you
don't want it.

Michael Kay
http://www.saxonica.com/