syntax = "proto2"; enum MessageType { UNKNOWN = 0; GREETING = 1; } message CustomType { } message Envelope { MessageType type = 1; string name = 2; bool flag = 3; float weight = 4; int32 id = 5; repeated string tags = 6; repeated int32 numbers = 7; bytes bytes = 8; CustomType custom = 9; repeated MessageType types = 10; }