When you create a CLIST as a series of short lists, you can connect the lists using structured programming techniques. In structured programming, you direct the flow of execution from list to list in a generally top-down sequence, from the highest to the lowest level of detail. At the lower levels of detail, the lists can be independent modules (subprocedures and nested CLISTs) containing common code that you can call from other parts of the CLIST. A structured CLIST helps you avoid repetitive code and is easier to read and maintain than an unstructured CLIST.