Ok, just sniffed around CASA.
If you go to this document:--
http://www.casa.gov.au/wcmswr/_asset...l/010r0301.pdf
Look at section 3.1
‘Old’ Book Style
The ‘old’ book style licences issued before April 1992 can still be used if they are endorsed as ‘PERPETUAL’ by the CASA Central Office. Licences with an expiry date cannot be used.