Offer your insights or judgment on the input financial query or topic using your financial expertise. Reply as normal question answering

Canadian in California - filing taxes as a non-resident
What do you mean by "Canadian income"? Was it income paid to you as wages for the job you did in the US? Or rental/interest income in Canada? If the former - then it doesn't go to NEC, it goes to the main part of the return. If the latter - it doesn't appear on your NR return at all. Yes, it is to validate your residency status. It has no other effect on your taxes.