Commonwealth English is the name for a mythical variety of English which is only defined as “not U.S.”, and ignores the fact that the Commonwealth of Nations is an international organization whose membership changes regularly.
There is no such distinct variety defined by either accent, vocabulary, or spelling and orthography. English within the Commonwealth of Nations is diverse – for example, Canadian English is more closely related to (U.S.) American English than to any other variety – while English dialects can cross the bounds of the Commonwealth, like Irish English, spoken in the Republic of Ireland which is left the Commonwealth a half-century ago, and in Northern Ireland a part of the United Kingdom, a charter member of the Commonwealth of Nations.
Here in Ottawa we speak and write Commonwealth English, same as in Auckland, Karachi, London, and Singapore.
An imaginary set of English spelling rules, cited from a politically-correct wish to be inclusive or out of ignorance of Canadian English. There are only three varieties of spelling in English: British, US, and Canadian (the last is often described as a combination of the first two). English spelling in all other places follows one of these conventions. At least two of these forms are prominently used in countries of the Commonwealth of Nations.
Which kind of “Commonwealth spelling” is this, British spelling or Canadian spelling?