Tree hierarchy

[DigiRev]

I'm making a chat server with a bunch of different rooms. Chat rooms will be stored in a "tree hierarchy" form, like this (think of a message board like this one):

Category 1
    Room 1
    Room 2
    Room 3

Category 2
    Sub category 1
        Room 1
        Room 2
        Room 3

I will be storing and using them from a UDT array, similar to this:

Type CHAT_ROOM
    dblID As Double 'ID of chat room.
    dblParentID As Double 'ID of parent room/category.
    strName As String 'Name of chat room/category.
    IsRoom As Boolean 'To tell if it is a chat room or a category.
End Type

Private udtRooms() As CHAT_ROOM 'Array to store all chat rooms.

There's actually a lot more properties than that, but that's the basic form.

I'm getting confused on how to set the parent ID for each item. I'm making a dialog in the server so I can create/edit the default chat rooms.

When someone joins a room the client will refer to the room's ID instead of the name, ie:

"JOIN #room number"

I attached a screenshot.