Occurrence Report
Any occasion concerning dangerous goods (accidents, incidents, other occurrences, such as misdeclared or undeclared dangerous goods) has to be reported to Austro Control GmbH (§12 Z 2 GGBG) within 72 hours (Attachment 1 - OPS 1.1225).
More information and definitions of occasions could be found in the ICAO Technical Instructions for the Safe Transport of Dangerous Goods by Air (Part 7, Chapter 4).