There seems to be a discrepancy between the use of the "sai_sac" field and the registration of this field. The use is based on a 2 octet value (proto_tree_add_item(tree, hf_gtp_sai_sac, tvb, offset, 2, ENC_BIG_ENDIAN);) while the registration is for a 1 octet value (..."Service Area Code (SAC)", "gtp.sai_sac", FT_UINT8, BASE_DEC,...). "gtp.rai_rac" suffers this same fate.