Choosing a Transaction Code from the History List 
Use
You can display a list of the transaction codes processed since you logged on (called a history list), and then choose a transaction code from that list.
Procedure

As of Release 4.6, the command field is closed by default. To display it, choose the arrow to the left of the Save icon: 
The command field appears: 
To hide it, choose the arrow to the right (outside) of the field.
at the right-hand end of the command field.The history list appears, displaying the transaction codes for all the transactions you have accessed in all of your sessions since you logged on. A sample history list is shown here.

This takes you to the initial screen of the task associated with that transaction code.