In a BI Publisher RTF template it is required to extract 2 variables.
The extraction is done through the following statements:
<?if:../../Tax_Summary_Lines_Section_S8/Summary_Taxable_Amt_ID8!="0"?>
<?if:position()=last()?>
<?xdoxslt:set_variable($_XDOCTX,'AllTax',../../Total_Extended_Price_WF_ID23)?>
<?xdoxslt:set_variable($_XDOCTX,'Tax',../../Tax_Summary_Lines_Section_S8/Summary_Taxable_Amt_ID8)?>
<?xdoxslt:set_variable($_XDOCTX,'NonTax',xdoxslt:get_variable($_XDOCTX,'AllTax - Tax'))?>
<?end if?>
<?end if?>
Q) It is this the proper way to do the substraction <?xdoxslt:set_variable($_XDOCTX,'NonTax',xdoxslt:get_variable($_XDOCTX,'AllTax - Tax'))?>