Last year's memorandum on who is responsible for what says this:
[Fences], if they are shown as a thin, dotted or no line on the strata plan then they are treated in accordance with the Dividing Fences Act and are treated as follows.
i. Divides two lots. Each owner is responsible 50%/50%.
ii. Divides one lot from common property. Owner 50% and the OC 50%.
iii. Divides one lot from the adjoining property. Adjoining owner 50% and the OC 50%.
However, if the fence is shown as a thick black line on the strata plan, i.e. a boundary fence round common property, it's the OC's responsibility.