It seems there is just as much confusion as "perceived discrimination" .
1) Most forms that ask you to identify race include only one box per race
2) If you check more than one box, often your answer is "invalid" or the computer/system will not accept it
Now if you insist on being identified as multi-ethnic, the person will usually get confused, insist you check only one box, or just shrug as say "I don't care".
Which is interesting bc if they don't care, and you can check ANY box, then what does race really mean?
Good luck on your study :)