The ATAR (Australian Tertiary Admissions Rank) for Tasmanian senior secondary students is typically based on the best five results in TQA level 3 courses, of which three must be from Year 12 (or 13) and two from that year or one other. A collaboration between UTAS and the TQA extends the processes used to determine ATARs to allow the inclusion of results in the High Achiever Program (HAP).
All TQA level 3 courses have the same size - size 15. HAP units run over only one semester and are about half the size of a TQA level 3 course.
The idea of the 'best five' results for students who include HAP results becomes the 'best five equivalent' results. A single HAP unit result counts as the equivalent of about half a TQA level 3 course. There is also a rule that only two HAP results can be included in an ATAR.
http://www.studentcentre.utas.edu.au/admissions/requirements.html#seniorsecondary