# ISDOC-4.1.8

Source: https://xmlvalid.com/rules/ISDOC-4.1.8

> Nepovinnou položku SecondarySellersItemIdentification lze uvést pouze v případě, že je uvedena také položka SellersItemIdentification.

- Level: error
- Rule sets: ISDOC 6.0.2 rules
- Context: `isdoc:Invoice/isdoc:InvoiceLines/isdoc:InvoiceLine/isdoc:Item[isdoc:SecondarySellersItemIdentification]`
- Test: `isdoc:SellersItemIdentification`

In English: SecondarySellersItemIdentification may be given only together with SellersItemIdentification.

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