Section: 28.4.2 Format of the S-NSSAI
Content: The structure of the S-NSSAI is depicted in Figure 28.4.2-1 Figure 28.4.2-1: Structure of S-NSSAI The S-NSSAI may include both the SST and SD fields (in which case the S-NSSAI length is 32 bits in total), or the S-NSSAI may just include the SST field (in which case the S-NSSAI length is 8 bits only). The SST field may have standardized and non-standardized values. Values 0 to 127 belong to the standardized SST range and they are defined in 3GPP TS 23.501[ System architecture for the 5G System (5GS) ]  [119]. Values 128 to 255 belong to the Operator-specific range. The SD field has a reserved value "no SD value associated with the SST" defined as hexadecimal FFFFFF. In certain protocols, the SD field is not included to indicate that no SD value is associated with the SST.