The issue there was that number of layers did not include normals,
while element size counts bytes used by normals. This sounds very
fragile and dangerous to work further. Also, one value can easily
be delivered from another, so it is redundancy going on here.
Possible difference now is that multires subdivision will copy
normals to a higher levels. Shouldn't be big of a problem, since
leaving old normals and updating coordinates is not correct either.
CCGKey caches information about the CCGSubSurf element layout. This
data, along with the CCG_* inline functions, allows access to
CCGSubSurf elements with an arbitrary number of layers (as opposed to
the hardcoded DMGridData structure which assumes xyz coordinates
followed by three normal components.)
The CCGElem structure is declared but not defined anywhere, just used
as a convenient type.
