# ISDOC-4.1.1

Source: https://xmlvalid.com/rules/ISDOC-4.1.1

> Pro typ dokladu 2, 3 a 6 musí existovat vazba na původní doklad. Konkrétně tedy pro DocumentType = 2, 3, 6 musí existovat element OriginalDocumentReference a musí byt neprázdný.

- Level: error
- Rule sets: ISDOC 6.0.2 rules
- Context: `isdoc:Invoice[isdoc:DocumentType = (2,3,6)]`
- Test: `isdoc:OriginalDocumentReferences/*`

In English: Documents of type 2, 3 and 6 (credit note, debit note, credit note to a taxed advance invoice) must refer to the original document: OriginalDocumentReference must be given and not empty.

## How to fix it

- Add `OriginalDocumentReferences/OriginalDocumentReference` with the number (`ID`) and date of the invoice it corrects.

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