A brokerage firm keeps a file of its brokers and a file of customers. One way to indicate which customerbelong to which brokerswould be for each customer record to have a field which gives the name of his/her broker. Observe that one would have to search through all the customer records in order to find all the customers belonging to a given broker.
Another way to organize the files is through linked lists. the customers of a given broker are linked alphabeyically, and the broke's record has a pointer giving the address of the first customer in his list. this is indicated in fig.9-9, where, say, broker Chandler has three customers, Brown,Murphy, and zimmerman.