# FX-SCH-A-000012

Source: https://xmlvalid.com/rules/FX-SCH-A-000012

> An Invoice shall have an Invoice issue date (BT-2).

- Level: error
- Rule sets: Factur-X MINIMUM rules 1.09, Factur-X BASIC rules 1.09
- Context: `/rsm:CrossIndustryInvoice`
- Test: `(rsm:ExchangedDocument/ram:IssueDateTime/udt:DateTimeString[@format='102']!='')`

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