When a pcap file uses one of the user DLTs (147 to 162) wireshark uses this table to know which protocol(s) to use for each user DLT.
This table is handled by an Section 9.7, “User Table” with the following fields.
One of the user dlts.
This is the name of the payload protocol (the lowest layer in the packet data). (e.g. "eth" for ethernet, "ip" for IPv4)
If there is a header protocol (before the payload protocol) this tells which size this header is. A value of 0 disables the header protocol.
The name of the header protocol to be used (uses "data" as default).
If there is a trailer protocol (after the payload protocol) this tells which size this trailer is. A value of 0 disables the trailer protocol.
The name of the trailer protocol to be used (uses "data" as default).