>>>>>Hi everybody,
>>>>>
>>>>>I've checked this link http://grammarist.com/spelling/cancel/ but I am not 100% sure which spelling should I choose. The software is written by US company, but may be used by US, Canadian, NZ and Australian clients. It may also be used internationally in other countries.
>>>>>
>>>>>So, just wondering what spelling do you prefer in your code?
>>>>>
>>>>>Thanks in advance.
>>>>
>>>>I wouldn't worry much about it. The meaning of the word is well understood by English speakers everywhere, even if there is a slight difference in spelling. Neither is incorrect.
>>>
>>>I have another case of, I believe, wrong usage of the word - I am not sure if I need to correct it, though.
>>>
>>>Let's consider this text
>>>
>>>"The incentive is satisfied if the Group Level (actually lesson level) for the event satisfies the specified criteria."
>>>
>>>For each individual criterion we perform a check whether conditions are satisfied or not and then print this kind of the message. To be 100% correct we need to use the word "criterion" here, not "criteria". However, I am not sure if it's worth the trouble of fixing all the code (because this kind of text is repeated over and over again in that class).
>>>
>>>What do you think?
>>
>>"Conditions" is plural, so shouldn't it be "criteria"?
>
>True. By conditions I mean - say, we want to define incentive as number of hours taught between 10 and 20. So, on the form we can specify low boundary and upper boundary (we can also specify the < = > sign for the comparison).
>
>So, given that information, do you think the word "criteria" is correct for this context?

I'm really not sure because I don't know what Group Level means. It again seems to indicate plural but maybe it doesn't.