//      EXEC PGM=BATCHPRG
//DD1   DD DSN=A,RLS=NRI,DISP=SHR

When the program BATCHPRG opens DD1, the data set is to be processed as a shared resource. NRI specifies that an application can read uncommitted changes made by other applications.

//      EXEC PGM=BATCHPRG
//DD2   DD DSN=B,RLS=CR,DISP=SHR

When the program BATCHPRG opens DD2, the data set is to be processed as a shared resource. CR specifies that an application can read only committed changes made by other applications.