[EM] preference swapping shenanigans in Australia

[Ken & Karla]

LAYTON Craig <Craig.LAYTON at add.nsw.gov.au> wrote, in part:
>
>Some people are beginning to question the wisdom of a preferential system
>because it appears to be conferring an inordinate amount of power onto this
>lunatic party (the power to topple governments).
=====
[KB]  Does the Australian system require a voter to rank every candidate for
an office else the ballot is invalid?  If so, would the distressing results
you've mentioned likely be different if voters could rank fewer than all the
candidates?

Thank you.

  --Ken Bearman
    Minneapolis Minnesota