# CII-SR-439

Source: https://xmlvalid.com/rules/CII-SR-439

> ChargeAmount should exist maximum once

- Level: error
- Rule sets: EN 16931 rules (CII) 1.3.17, EN 16931 rules 1.3.16 (CII)
- Context: `/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:IncludedSupplyChainTradeLineItem/ram:SpecifiedLineTradeAgreement`
- Test: `count(ram:NetPriceProductTradePrice/ram:ChargeAmount) = 1`

Validate a document against these rules: https://xmlvalid.com/validate