Changes have been made to allow you to start entering new data required for AVETMISS 8, for enrolments that are starting or continuing into 2018.
AVETMISS generation has not yet been made available. In VETtrak 18.1 (due in the first week in January) you will be able to generate NAT files in either AV7 or AV8 format.
All changes are documented in the 17.3 Release notes, alternatively there is a summary of major AVETMISS changes available here.