utc not necessarily i believe sd has tighter electrical specifications than sd x such as lower voltage tolerances and higher current tolerances so a sd x device may but would not necessarily qualify as an sd device it would need to be meet the electrical specs of sd before it could be able to offically support sdhc and carry the sdhc logo it is possible that some sd x devices will already meet this spec just because they were designed well from the start but they would need to be tested to ensure they meet the sd electrical spec and also have a firmware upgrade july