+#) Fields in the generated structs are ordered by the tag number, instead of the natural ordering in .proto file.
+#) Unknown fields are not preserved when decoding and re-encoding a message.
+#) Reflection (runtime introspection) is not supported. E.g. you can't request a field by giving its name in a string.
+#) Numeric arrays are always encoded as packed, even if not marked as packed in .proto. This causes incompatibility with decoders that do not support packed format.
+#) Cyclic references between messages are not supported. They could be supported in callback-mode if there was an option in the generator to set the mode.