Code specifying the additional allowance, see code list at https://big.btwentyfour.com/codes#id3

invoic_Examples
 <allowances name="unspecified allowance" code="ACA" percent="10" amount="40.00" /> 
invoic_XPATH

/b24Message/invoice/allowances/@code

invoic_Required
No
invoic_Type
Text
invoic_Sort
23200