What's wrong with this Foundation call?

Declare Function NSMakeSize Lib Foundation (w as single, h as Single) As NSSize32Bit

Foundation being “Foundation.framework”, NSSIze32Bit a struct of 2 singles. It crashes with a

[quote]Symbol not found: _NSMakeSize
Expected in: /System/Library/Frameworks/Foundation.framework/Versions/C/Foundation[/quote]
error message.

Similar calls to the same framework do work …

Thanks! So I can’t use it as an API call? Where do you find that information?
When I look into Apple’s dev docs, it’s declared as a function with a return value … So how can one tell if it’s a macro or a real method by the docs?

read the c files, please.

Thanks a lot, you two! Call me blind or stupid, but I still can’t find what’s a macro and what’s a function there – but anyway, I’ll revert this function to “my” Xojo “macro” then. Thought I could speed it up a bit – not that it would be that slow …