Number,Description/Meaning,Reference
128,Send RTT Estimate,[RFC6323]
129-183,Unassigned,
184-190,Reserved for experimental and testing use,[RFC4342]
191,Unassigned,
192,Send Loss Event Rate,[RFC4342]
193-247,Unassigned,
248-254,Reserved for experimental and testing use,[RFC4342]
255,Reserved,[RFC4342]