We seem to be getting lost in semantics and linguistics here, partly my fault I suspect. Let's get back to the facts for a moment.
As we know, ANZAC is a military acronym, which stands for Australian and New Zealand Army Corps. Therefore when you celebrate 'ANZAC Day' you are celebrating the Australian and New Zealand Army Corps. That includes all the British and Indian Brigades and Divisions, and units of various other nationalities that formed part of ANZAC at one time or another. It does not include the AFC, the RAAF, the RAN, the RNZAF, the RNZN, the 2nd AIF, or the 2nd NZEF, except for the shortlived ANZAC formation during the '41 Greek campaign. Nor does it include Australians and New Zealanders who served in British or other national Armies, Navies, or Air Forces. Most obviously it does not include servicemen and women since WWII.
That's why we've always celebrated 'Anzac Day'. From the very beginning the word 'Anzac' was coined in reference to Australians and New Zealanders, irrespective of Command, and the word 'Anzac' retained currency after the two ANZAC Corps ceased to exist in 1917. It remains current today, and notwithstanding any trans-Tasman confusion that may exist, the rest of the world appears to be in little doubt as to its meaning, certainly if their English dictionaries are any guide:
UK. Oxford: Anzac (noun):
1. A soldier in the Australian an New Zealand Army Corps (1914-1918)
1.1 informal: A person from Australia or New Zealand, especially a member of the armed services.
USA. Merriam-Webster: Anzac (noun): a soldier from Australia or New Zealand
Thanks to this uniting word, we are able to celebrate Anzac Day as a commemoration and a tribute to ALL Australian and New Zealand servicemen and women, past and present, and express our desire to associate ourselves with the values they represent. These values we loosely define as 'the Anzac spirit', and we would like to think the Anzac spirit informs our national character both in Australia and New Zealand. We do not refer to it as the ANZAC spirit, or the RAAF spirit, or the RNZN spirit, because these terms are not all-embracing.
You'll find a brief summation of the Anzac spirit on the AWM website, including the origins of the word 'Anzac' itself, and I'd suggest it's required reading for this debate:
http://www.awm.gov.au/encyclopedia/anzac/spirit.asp
Also worth noting are NZNWM guidelines for use of ANZAC or Anzac: "We recommend using the term 'ANZAC' with all capitals only when referring to the specific Corps. For all other uses 'Anzac' is preferred."
http://www.mch.govt.nz/nz-identity-h...zac-guidelines