Subset Type

The subset type specifies the organization of the subset and identifies the key or keys, if any. Five subset organizations are available. For more information on the subset organizations, refer to Structure Formats.

  • Bit vector

  • Index sequential (I-S)

  • Index random (I-R)

  • Ordered list (O-L)

  • Unordered list (LIST)

When no subset organization is specified, one is assigned by default as shown in Default Subset Organizations.

Table 13. Default Subset Organizations

Subset Type

Organization If Key Assigned

Organization If No Key Assigned

Disjoint subset

Index sequential

Unordered list

Embedded subset

Ordered list

Unordered list

All subset and data set combinations are valid with the following exceptions:

  • Bit vector subsets can refer only to disjoint standard data sets which do not contain variable-format records.

  • Index random and bit vector subsets cannot be embedded.

  • No subset can refer to an ordered data set.

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