> What am I doing wrong?

well you haven't shown any sopurce code, so we have to guess, but
presumably you get 0 bcause there are no preceding siblings.
that is children of the same parent.  If each Accruals element just has
a single Accrual child, then that will be the case.


> I know could use "position()", but after I solve this problem I need to apply a filter to the PSIBS 
> value.


Most likely you just need to do the filter before you use position.


<xsl:for-each
select="expensys:Lines/expensys:Line/expensys:Accruals/expensys:Accrual[some
filter goes here">

<txn:PSIBS>
<xsl:value-of select="position()"/>
</txn:PSIBS>


David



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