title: What is C2 surface in CAD, what does C2 mean?
body: <p>C2 surface/mesh is well-known surface in CAD/OpenGL. But I just want to know that what is C2 means ? </p>
  
  <p>C means what ? </p>
  
  <p>2 means what ?</p>
  
  <p>C2 = acronym ???????  </p>