BR-GA-0
When using the G-account extension, the CustomizationID must specify this.
error: the document is invalid
What the rule checks
As the rule set's publisher wrote it. The rule runs on every element the context matches, and fails where the test is false; the validator reports the line of that element.
Context
//cbc:CustomizationID
Test
contains(., '#conformant#urn:fdc:nen.nl:gaccount:v1.0')
Checked with Netherlands SI-UBL 2.0 G-account Invoice