I am genuinely curious why not. Interesting to know that history about php! A middle ground might have been to use a transliteration such as CNContactLabelRela

I am genuinely curious why not. Interesting to know that history about php! A middle ground might have been to use a transliteration such as CNContactLabelRelationBiaoJie. Your point about input makes sense in that it's technically possible to type the English identifier without Chinese input methods, although I would be surprised if anybody typed that long-ass English identifier without IDE completion or copy-paste either! The point about being able to more easily compare, I disagree with - the long identifiers are hard to check. IMO if an API exposes an uncommonly-known but well-defined concept, I think it's acceptable, and better, to ask users of the API to learn the concept before use rather than paraphrase it. It better matches what developers are likely going to try to do: if anyone is ever going to write a program that has to care about this case, I'm pretty sure the spec isn't going to be something like "if the contact is the user's elder female cousin who is either the user's mother's sibling's daughter or the user's father's sister's daughter..." - it's likely going to say, if not in Chinese, "if the contact is the user's 'biaojie'..." There is good precedent for this kind of preference for expressing concepts that aren't broadly familiar in technical APIs. You'll get some symbols containing words like AffineTransform or CMYK in it, and probably many programmers wouldn't know what they stand for either until they need to learn what they are, but that's ok and better than dumbing down the API to something like RotationOrTranslationOrResizingOrCombinationThereOf or PrimarySubtractiveColorSystem.