Specifications update for PINT-SG

The Peppol PINT-SG BIS Billing general data model's first version introduces features distinct from SG BIS Billing 3.0.
What are the new features?
The following features have been introduced:
- cbc:IssueTime - An optional element designed to capture the issued time;
- cac:InvoiceLine / cac:OrderLineReference / cac:OrderReference / cbc:ID - Enables referencing multiple PO numbers to the item li…