Ann: Quarterly Activities Report, page-19

I'd always assumed the rule's algorithm would look like: is your % holding right now >20% and also more than 3 percentage points higher than it was 6 months ago? If so, creep rule has been violated. That way it doesn't matter how it happened, whether you bought shares on the market, or in an off-market block trade, or you absorbed a smaller company that held 4% of the float, or you exercised a bunch of options, or shares evaporated due a buyback, or you'd sold a bunch of puts and someone exercised them, etc.

As it turns out, that's probably *mostly* accurate, but https://content.allens.com.au/the-allens-handbook-on-takeovers-in-australia/exceptions-to-the-rule/ would seem to suggest there are more exceptions than I'd assumed. Absorbing a smaller company that had a moderate interest is actually ok if it passes a common sense sniff test, & there are a few other exceptions - still, the exceptions by their nature seem to strongly imply that moving from X% to (X+3)% is the problem, not the act of purchasing shares itself.