GL_NV_copy_buffer
http://www.opengl.org/registry/specs/NV/copy_buffer.txt
GL_NV_copy_buffer

	GL_COPY_READ_BUFFER_NV 0x8F36
	GL_COPY_WRITE_BUFFER_NV 0x8F37
	void glCopyBufferSubDataNV (GLenum readtarget, GLenum writetarget, GLintptr readoffset, GLintptr writeoffset, GLsizeiptr size)