rem: unsigned char* base() { return reinterpret_cast<unsigned char*>( accessor::rw_base( idx_ ) );
add: const unsigned char* base() const { return reinterpret_cast<const unsigned char*>( accessor::ronly_base( idx_ ) );
context: 		unsigned char* base() {			return reinterpret_cast<unsigned char*>( accessor::rw_base( idx_ ) );		}