In which contexts do I have to use canceling or cancelling? Google returns 15.6 million results with canceling and 18 million with cancelling, so I don't know what is the good spelling. Cancelling is BE and canceling is AE.

Understanding the Context

I can change the language on my Word 2003 even within sentences. It copes easily with several different Englishes or other languages in one document. I am sorry I cannot answer your question about regions 'accepting' the other form but it would certainly be recognised as a standard English. I hope the first bit of this reply is helpful Not quite the same as checking a queue and then cancelling something.

Key Insights

Your example is from a computing context, true, but the term veto is not normally used for stopping requests. I think "cancelling" an event (in my calendar) pretty much covers it. I thought I had a good understanding of the difference between "postpone" and "cancel," but lately I've seen officials using postpone instead of cancel, perhaps to soften the blow of cancelling a fun event. So that travel, parcel, cancel, revel etc., take such forms- traveller, travelling, travelled; parcelling, parcelled; cancelling, cancelled; reveller, revelling, revelled, re. For words with stress on second syllable, the spelling remains the same, as in case of American English.

Final Thoughts