Cause and affected field
If you offer a cash discount, use uppercase hash-separated SKONTO, TAGE and PROZENT segments, two decimal places for the percentage, and a newline after each entry. Add BASISBETRAG only when the discount applies to part of the amount due. The example means 2% within 10 days; use your actual agreement.
Rule family: XRechnung 3.0.2. The finding from the ruleset actually executed remains authoritative.
Correction and example
#SKONTO#TAGE=10#PROZENT=2.00# (no newline)#SKONTO#TAGE=10#PROZENT=2.00#
Validate again
Correct the original in your invoicing system and inspect the replacement file. Ask the supplier to correct an incoming invoice.