David, I think the information comes mainly from Vic passenger arrivals, and from the comprehensive indexes to Vic births, marriages, and deaths (now for sale on CDs - think they used to be on fiche/film?).
For example, the deaths index has:
Surname:
Given Names:
Father:
Mother: (includes maiden name)
Death Place:
Age:
Year:
Reg Number:
Event: D

Birthplaces were given on the Vic marriage indexes.

Sue