Changing the array pointer in CVA's

If I was to change the glVertexPointer or glTexCoordPointer during a locked CVA what would occur? Also is there any way to lock a section of memory before TexCoordPointer and VertexPointer have been called?

The effect of changing the pointer is undefined. Most likely you’ll generate an access violation

>>If I was to change the glVertexPointer or glTexCoordPointer during a locked CVA what would occur?