Mustang 2.0.3 was released on 2020-12-06 and contains minor bugfixes, namely

• #201 correct embedded files in XRechnung
• don’t write “null” as paymentDescription if no Bank account is specified
• generic and unitcode/categorycode improvements (thanks to weclapp-dev) PR #207

Additionally

• support credit notes (additionally to corrected invoices)
• transaction calculator getGrandTotal now public, allowing to compare XML grant total with own calculations
• programmatically switch to XRechnung 2.0 if invoked after 2021-01-01