Soul names are a protection against sending, which can easily reveal all of its user to the recipient. Soul names essentially divide the elves inner-most self away from the rest of their mind, making it inaccessible to anyone - sending or otherwise - that does not have its key, the user's soul name. This protection is only used by Wolfriders: the rest of the elves wear their soul names as their usename. (I think there's a line to this mention in the novel Captives of Blue Mountain: Cutter is surprised that Winnowill wears her soul name so openly, or somesuch?)
One of the main signs of recognition is that the couple will instinctively share their soul names during the link. Though rare, elves who are particularly close will privately share their soul names with each other as an ultimate sign of their bond; for example Cutter and Skywise, who consider themselves "brothers in all but blood", know each others soul names.
Usenames[]
Wolfrider style: Redlance, Stonefist, Treestump
Normal: Tyleet (gift of healing), Leetah (healing light), Shenshen (bright bright), Rayek (child of the rocks)
'Normal' style names all have meanings in the elfin language. (Need to dig up the old Yahoo group and forum thread about it.)
Known Soulnames[]
Dyrr[]
Dart discovered his when his cocoon was opened by Serrin, and they Recognised.
Eyrn[]
Moonshade discovered her soulname when she Recognised Strongbow in the middle of archery practice.
Fahr[]
Skywise discovered his during a fight with Cutter, in which they had a strange quasi-Recognition.
Lree[]
Dewshine had hers discovered by Tyldak, when they Recognised in the Blue Mountain.
Sohn[]
Tyleet discovered hers when she Recognised her tribemate Scouter.
Sur[]
One-Eye
Tam[]
Cutter
Twen[]
Nightfall
Ulm[]
Redlance
Wyl[]
Strongbow
Zheel[]
Ember
Grenn[]
Bearclaw
Dehl[]
Joyleaf