Several CVs are reserved for identifying your decoders.
CV07 is the manufacturer's version ID. Manufacturers can use this CV to store information about the part number or version number of the decoder. In some decoders this is a read only CV, in others it is a read/write CV. Where CV07 is read only, the information loaded by the manufacturer will be available. If CV07 was read/write, the value may have been changed and will not necessarily be what the manufacturer originally loaded into the decoder.
Version IDs do not necessarily represent code changes made to decoders and they may or may not be in any certain alphabetic or numeric order. The same Version ID may be used for more than one decoder but the code may not be the same.
CV08 is the manufacturer's ID. Each DCC manufacturer uses a unique ID code so you can determine which manufacturer built the decoder. Digitrax ID is always 129/x81.
CV105 & CV106 are the user private IDs you can program any information you choose into these CVs.