I am confused with the model numbers from Dahua. The have numbers like N45DJ62, A22CJ62, DH-IPC-HDBW8232EN-Z-SL, 6QE240VNI, etc. There seems to be no consistency so what do all those numbers and letters mean (I searched the Dahua forum but couldn't find anything). I am looking at the different versions of the 5442 camera which everybody seems to like but can't find that number anywhere when going on dehuasecurity.com