The Transfer of Land (Stratum Estates) Act 1960 (VIC) allowed for the creation of stratum units. This provides for multiple ownership of subdivided lots, where the owner of a lot can obtain a certificate of title. However, under this legislation, a lot is essentially a specified dimension of airspace, which provides its title holder with a right to occupy the floor space of a building in that airspace.
The use of stratum lots required the use of a service company and an associated service agreement to formalise the relationship between the owners and the service company. Because a lot is, in effect, airspace, it was considered difficult to mortgage and thus is not commonly used.