It would be nice to think that stamp catalogues are comprehensive, but they're not. I've scanned a few minor Australian varieties to add to my store, and a few of them are unlisted in the Australian Commonwealth Specialised Catalogue. I've seen them before, and I know they're constant, yet I can't provide a catalogue number for them. The ACSC has always irked me for this, as page after page of content is dedicated to proofs and other items that 99% of collectors will never see, yet they can't find room for all known varieties.