This section is used to sanitize tunneling layers. At the moment, the only tunneling technique that is support is the AYIYA layer used by IPv6 over IPv4 tunnels provided by SIXXS. Their tunneling layer allows transporting IPv6 frames over UDP, and contains a identity and signature that are basically credentials for the tunnel connection.
The reason why this layer can be processed by TraceWrangler is pretty simple: I use SIXXS tunnels for IPv6 R&D as well as teaching classes. So I need that functionality myself, and that's the reason why I added a parser for this.