Why do I see THROW in a C library?

When I do: less /usr/include/stdio.h (which is only a C library - nothing to do with C++)

I see __THROW after quite a few function declarations. Also, comments above a few functions say that 'This function is a possible cancellation point and therefore not marked with __THROW' What is all this for?

throw is meant to be for exception handling...but as far as I know, C doesn't provide any support for it.