In the Win32 x86-64 CONTEXT structure, there are members named VectorRegister and VectorControl. What are those for?
The XMM registers are stored in Xmm0 through Xmm15. Extended vector registers such as the YMM and ZMM registers are stored in "XSTATE" extended context structures, not in the VectorRegister array. Also, there being 26 vectors in that array is really weird.