Dissector Header Labels

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Hello. I have written a dissector for a subset of a protocol called TC that has two subfields. Let's call this implementation "TC_Subset" and the two fields the Primary and Segment fields. I would like the wireshark display for the dissection to look like the below, where > and V indicate collapsed and expanded trees, respectively;

> Frame 1
V TC_Subset
  > Primary Header
  > Segment Header

Unfortunately, it currently looks like this:

>Frame 1
V TC_Subset
   > TC_Subset
   > TC_Subset

I think I know why, but I don't know how to fix it. I'll start by showing the relevant areas of code and point out where I think the issue is. I believe it's from a combination of things in the dissect_ and register_ methods.

"dissect_tc" excerpt

static int
dissect_tc(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data _U_)
{
    //OFFSET IS IN OCTETS
    int          offset          = 0;
    proto_item  *tc_packet;
    proto_tree  *tc_tree      = NULL;
    proto_item  *primary_header  = NULL;
    proto_tree  *primary_header_tree;
    proto_item  *segment_header = NULL;
    proto_tree  *segment_header_tree;
    ...additional set up and definitions of things like length, etc...

    /* Set up the base tree */
    tc_packet = proto_tree_add_item(tree, proto_tc_subset, tvb, 0, length, ENC_BIG_ENDIAN);
    tc_tree   = proto_item_add_subtree(tc_packet, ett_tc);

    /* build primary header tree */
    primary_header = proto_tree_add_item(tc_tree, proto_tc_subset, tvb, offset, TC_PRIMARY_HEADER_LENGTH, ENC_NA);
    primary_header_tree = proto_item_add_subtree(primary_header, ett_tc_primary_header);
    ...program tree accordingly...

    /* build segment header tree */ 
    segment_header=proto_tree_add_item(tc_tree, proto_tc_subset, tvb, offset, TC_SEGMENT_HEADER_LENGTH, ENC_NA);
    segment_header_tree=proto_item_add_subtree(segment_header, ett_tc_segment_header);
    ...rest of method, not related to the problem...

Next, let's look at a small section of register_tc.

"register_tc" excerpt

void
proto_register_tc(void)
{
    static hf_register_info hf[] = ...define all fields for both headers in this one array...

    /* Setup protocol subtree array */
    static gint *ett[] = {
        &ett_tc,
        &ett_tc_primary_header,
        &ett_tc_segment_header
    };

    ...

    /* Register the protocol name and description */
    proto_tc_subset = proto_register_protocol("TC_Subset", "TC_Subset", "tc_subset");

    /* Required function calls to register the header fields and subtrees used */
    proto_register_field_array(proto_tc_subset, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));

Note that in the definition of the primary header and segment header variable, I'm passing in "proto_tc_subset" both times. That's where the label is coming from. I think I need to pass in something else there in order to get the label to be what I'd like to see instead of just repeating "TC_Subset", but I'm not sure how to define such a thing.