SUM() different nodes of an XML

Question

I have an XML like below in BI Publisher-

<ROW1>
  <TOTAL_RETAIL>10.95</TOTAL_RETAIL>
  <TOTAL_TAX> 1.8</TOTAL_TAX>
  <TOTAL_SHIPPING>7.95</TOTAL_SHIPPING>
</ROW1>

<ROW1> does not repeat. Now as I understand to do a SUM of a node I can use XPath function sum() like <?sum(.//TOTAL_RETAIL)?>. This will sum the values of the node TOTAL_RETAIL only, I want the sum of TOTAL_RETAIL, TOTAL_TAX, and TOTAL_SHIPPING. Is there a way I can write the sum function to achieve this.

Note- It cannot be handled programmatically i.e. using variables etc. since its inside a Report template and has to be defined as <?sum(...)?> this values will be mapped to a specific cell in an excel report template.

Answer 1

Try

<?sum(.//TOTAL_RETAIL | .//TOTAL_TAX | .//TOTAL_SHIPPING)?>

| is the union operator, so the argument you're passing to sum() is the union of the three sub-expressions.