Control Data Corporation 3300 Reference Manual page 53

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When the DE PENDING ON option is specified in a data description in the
File Section, records written on external devices will be variable in length
depending on the value of data-name-I. DEPENDING ON may appear only
once in a record description entry and must be at the last major level of
the record.
The KEY IS option indicates that the repeated data is arranged in ascendil'lg
or descending order according to the value of the key data names (data-
name-2, data-name-3, etc.). This option is required when a SEARCH ALL
statement is used in the Procedure Division to search the table of repeated
data. The key data names are listed in descending order of significance.
Data-name-2 either names the entry containing the OCCURS clause or names
an entry subordinate to the entry containing OC CURS.
If
data-mune-3 or any succeeding key data names are used, each must name
an entry subordinate to the group item which is the subject of the entry con-
taining OCCURS. Except when data-name-2 is the subject of the OCCURS
clause, none of the key data names can be the subject of, or subordinate to
an entry containing an OCCURS clause.
The INDEXED BY option is required if the subject of this entry (or if it is a
group, an item within it) is referred to by indexing or is referenced by the
SEARCH statement. The index name is not defined elsewhere since its
allocation and format is controlled by the compiler. It is not data, and cannot
be associated with any data hierarchy. However, an index name must be
initialized by the SET statement before it is used as a table reference.
Index name items are one computer word in length and are in binary format
(COMPUTATIONAL-I) .
The VALUE clause must not be stated in a data description entry which
contains OCCURS or is subordinate to an entry containing OCCURS. This
rule does not apply to condition name entries. Initial values of items in
working storage may be specified in the following manner:
The table is described as a record with contiguous data description entries
each of which has a VALUE clause as well as other clauses, (USAGE,
PICTURE, etc.) required to complete the description. The table must be
specified again with a REDEFINES clause to show its hierarchical
structure. The entries subordinate to the REDEFINES entry are repeated
because of the OCCURS clause; but they must not contain VALUE clauses.
An alternate method can be used when the table elements do not require
separate handling because of usage, synchronization, etc. In this case,
the value of the entire table can be specified in the entry defining the
table. The lower level entries specify the hierarchical structure of the
table with OCCURS; they cannot contain VALUE clauses.
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