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Chapter 4. Storage management software > Partitioned organized (PO) data sets - Pg. 150

4.22 Partitioned organized (PO) data sets (PO) data set (PDS) PO.DATA.SET DIRECTORY A B A C C B MEMBERS Figure 4-32 Partitioned organized (PO) data set Partitioned organized (PO) data sets Partitioned data sets are similar in organization to a library and are often referred to this way. Normally, a library contains a great number of "books," and sorted directory entries are used to locate them. In a partitioned organized data set, the "books" are called members, and to locate them, they are pointed to by entries in a directory , as shown in Figure 4-32. The members are individual sequential data sets and can be read or written sequentially, after they have been located by directory. Then, the records of a given member are written or retrieved sequentially. Partitioned data sets can only exist on DASD. Each member has a unique name, one to eight characters in length, and is stored in a directory that is part of the data set. The main benefit of using a PO data set is that, without searching the entire data set, you can retrieve any individual member after the data set is opened. For example, in a program library (always a partitioned data set) each member is a separate program or subroutine. The individual members can be added or deleted as required. There are two types of PO data sets: Partitioned data set (PDS) Partitioned data set extended (PDSE) Chapter 4. Storage management software 143