This annex describes the serial presence detect (SPD) values for all DDR4 modules. The SPD data provides critical information about all modules on the memory channel and is intended to be use by the system's BIOS in order to properly initialize and optimize the system memory channels. The storage capacity of the SPD EEPROMs is limited, so a number of techniques are employed to optimize the use of these bytes, including overlays and run length limited coding. All unused entries will be coded as 0