Thanks for the explanation talkwrench. It seems to me that there are two issues at play here - the ALAEA rules and the CASA regulations
From the ALAEA rules
3.1 The Association shall consist of an unlimited number of persons employed or usually employed as engineers licensed to undertake, supervise and certify the maintenance of any one or more of the components, items of equipment, and/or systems (including associated equipment) in the airframes, engines, electrical systems, radio systems,and/or instrument systems on aircraft operating within the Commonwealth of Australia, its Territories and/or overseas from the Commonwealth of Australia
3.2 And any persons employed by Forstaff Pty Ltd or its subsidiaries or successors who perform, administer, or work in connection with, the refurbishment, reconfiguration or heavy maintenance work on aircraft at Avalon Airport in the State of Victoria, excluding persons employed in the occupation, industry or calling of storeworker.
The interpretation of those rules may be what's in dispute between the "rival unions", in particular 3.1.
Again my understanding is that the CASA stuff relates to the changes brought in last year as outlined on this link
http://www.casa.gov.au/wcmswr/_asset...t66booklet.pdf