RE: using xsl:key to generate list of back references

> will it be much faster, do you think, having a dedicated "same-nodes"
> comparison operator? or just make for more readable XSL?

I'd expect that in Saxon, for this predicate, the difference is noticeable,
but whether it affects the overall stylesheet execution time is anyone's
guess. 

Another technique is 
select="//ptr[count(.|key('targets',@target)[1])=1]">

And incidentally:
select="/descendant::ptr[count(.|key('targets',@target)[1])=1]">

might save you a sort. (Saxon will do this optimisation for you in some
cases but probably not here)

Mike K


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