There are some misleading sentences in this article. > The C stands for continuity and the superscript zero means the curves on the embedded surface have no de

There are some misleading sentences in this article. > The C stands for continuity and the superscript zero means the curves on the embedded surface have no derivatives, not even a first. This is not exactly true. C maps maybe have higher derivatives and maybe they don’t. Certainly, C isn’t a class of only continuous mappings that don’t have the first derivative. Also, the example with the letter U is bad (it tries to make a point, and it fails in doing so). A U-shaped curve can be perfectly smooth at all points. It would be “problematic” if we, for example, made the letter U by “glueing” a part of the circle and two segments.