Value-of a single node & sum of several nodes

I am working with financial data using the XBRL taxonomy (e.g. financial
statements & financial reporting)

I have a complex tree structure and need to extract a single value from
a node, not its decendents, what XSL do I use?
    Some code:
    <xsl:value-of select="balanceSheet/asets.currentAssets" />   <!--
gives me all decendents -->


I also need to create subtotals for specific node sets and have not been
able to make the "sum" function work??
    Some code:
    <xsl: value-of select="sum(//accountsPayableAndAccruedExpenses)"
<!-- gives me unknown method-->

Thanks - Skip ... a novice

--
----
Clinton E. White, Jr. (Skip)
http://www.accounting.udel.edu/skipstuff/skip3.html
Associate Professor of Accounting & MIS
Area Head MIS
University of Delaware, Newark, DE 19716
Phone: (302) 831-6902   Fax: (302) 831-4676



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