The theoretical and conceptual considerations for developing the classification were tempered by other considerations such as the practical usefulness of the classification for collecting data from both statistical and administrative collections, the analytical usefulness of data collected within the framework of the classification, and the size of the categories at each level of the classification in terms of the number of Australian adherents.
Generally, the classification criteria were applied in a straightforward manner. However, some decisions in regard to the identification of Religious Groups and the progressive grouping of units were made on the basis of whether it would be possible to collect data in relation to certain religious sub-sets or whether data for particular religions would be more useful if classified in a broader or finer manner. These decisions were made in consultation with religious and ethnic communities, religious experts and users of religious data.
One effect of these constraints on the classification has been that some religious groups which are significant in a world context are not separately identified in the structure, some Broad Groups are limited in the number of Narrow Groups they subsume, and some major world religions are represented at levels below the Broad Group level. The most notable effect has been in the large number of Narrow Groups and Religious Groups represented as subsets of the Broad Group Christianity.