# BR-28

Source: https://xmlvalid.com/rules/BR-28

> The Item gross price (BT-148) shall NOT be negative.

- Level: error
- Rule sets: EN 16931 rules (UBL) 1.3.17, EN 16931 rules 1.3.16 (UBL), Romanian RO e-Factura rules (UBL) 1.0.9
- Context: `cac:InvoiceLine | cac:CreditNoteLine`
- Test: `(cac:Price/cac:AllowanceCharge/cbc:BaseAmount) >= 0 or not(exists(cac:Price/cac:AllowanceCharge/cbc:BaseAmount))`

> The Item gross price (BT-148) shall NOT be negative.

- Level: error
- Rule sets: EN 16931 rules (CII) 1.3.17, EN 16931 rules 1.3.16 (CII), Factur-X EN 16931 rules 1.09.2
- Context: `//ram:IncludedSupplyChainTradeLineItem`
- Test: `(ram:SpecifiedLineTradeAgreement/ram:GrossPriceProductTradePrice/ram:ChargeAmount >= 0) or not(ram:SpecifiedLineTradeAgreement/ram:GrossPriceProductTradePrice/ram:ChargeAmount)`

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