Not necessarily, and it is up to what you plan to do. However, do use it as an ultimate reference. Each function in the Fusion GUI has a corresponding PMBus command. The UCD90xxx PMBus Command Reference contains not only protocol information but also a description of the device behavior of each function. If a customized software driver is required to develop to communicate with the UCD90xxx device, this UCD90xxx PMBus Command Reference is necessary.
UCD90xxx PMBus Command Reference
For more FAQ please check the following document.