So, to get all the information on a job, in order to create an invoice, you would start at the Job Card, get the info there, then look up to get the client address from the parent Client Card, and then look down to all the children Expense Cards.
If you wanted to get a list of all the client addresses for a mailing list, you could just look across the client level (look at all the Client Cards).
HyperArchy uses one HyperCard stack for each level. This example covers three stacks named Clients, Jobs, and Expenses. Every card has hidden lists in it for keeping track of the Parent Card to which it is attached, and for keeping track of the Child Cards attached to itself. As you use HyperArchy to make new cards or delete unused ones, HyperArchy keeps those lists up to date. You can use HyperArchy buttons to jump from a card to its parent, or to its children.