Let's compare this to a completely different field: cookbooks.
Recipes themselves aren't copyright protected. However, specific instructions for the recipes are protected.
In addition, though individual recipes aren't protected, a collection of recipes is protected.
There is a line, though, between copying a few recipes, and an entire collection. That line is not easy to define, but that doesn't preclude the existence of such a line.
So – is an API considered a single recipe? Or is it a "recipe collection?" That seems to me to be an important distinction.
If you were to copy one set of API function names that cover a limited area, then it could be argued that you used just one "recipe" and that it would be OK. However, if an entire collection of API function names across a very broad range of categories was copied, then it is harder to argue that you didn't copy any entire collection, and not just an individual recipe.
Recipes themselves aren't copyright protected. However, specific instructions for the recipes are protected.
In addition, though individual recipes aren't protected, a collection of recipes is protected.
There is a line, though, between copying a few recipes, and an entire collection. That line is not easy to define, but that doesn't preclude the existence of such a line.
So – is an API considered a single recipe? Or is it a "recipe collection?" That seems to me to be an important distinction.
If you were to copy one set of API function names that cover a limited area, then it could be argued that you used just one "recipe" and that it would be OK. However, if an entire collection of API function names across a very broad range of categories was copied, then it is harder to argue that you didn't copy any entire collection, and not just an individual recipe.