COBOL Manual for TNS/E Programs (H06.08+, J06.03+)

◦ When the data item is an independent elementary data item, you must define it in a
level-01 or level-77 data description entry in the Linkage, Working-Storage, or the
Extended-Storage Section.
◦ When the data item is a subordinate part of a record, you must define it in a data
description entry (with a level number in the range 02 through 49) associated with the
appropriate record description entry.
◦ When the data item is a redefinition of another item, you must define it in a data
description entry (with the same level number as the item it redefines) associated with the
appropriate record description entry or level-77 data description entry.
◦ The syntax and semantics of entries with level numbers 66 and 88 are explained in later
topics of this section.
• Constraints on Clauses of the Data Description Entry
Each data description entry must begin with the level number. If a data-name or the keyword
FILLER is specified, it must immediately follow the level number. The characteristics of the data
item determine which of the clauses are required or optional. Clauses that appear can do so
in any order. No clause can appear more than once.
◦ Data Name or FILLER Keyword
If the data-name appears, it specifies the name of the data item being described.
You can give an entry a name so that the name can be used to refer to the entry. If you
do not need to refer to the entry, you can give it the name FILLER, or omit the name entirely.
Such unnamed or FILLER items act as place holders in records where not all the fields are
referred to or as convenient names for constants, such as in report headings.
When the level number is 01, the data item is a record, and the data-name is sometimes
referred to as a record-name. In this case, the data-name must be specified if the data
description entry contains the EXTERNAL clause or if the data description entry is associated
with a file description entry that contains the EXTERNAL clause. If neither the data-name
nor the keyword FILLER is specified, it is as if the keyword FILLER had been specified.
When the level number is 77, the data item is an independent (or noncontiguous)
elementary data item, and the data-name (not FILLER) must always be specified.
◦ REDEFINES Clause
The REDEFINES clause, when it appears, must immediately follow the data-name or FILLER
keyword. If it does not, the compiler issues a warning, because COBOL requires
REDEFINES to precede all other clauses.
◦ EXTERNAL Clause
The EXTERNAL clause can be specified only for data description entries within the
Working-Storage or Extended-Storage Sections whose level number is 01. It cannot be
specified in a data description entry containing a REDEFINES clause.
◦ PICTURE Clause
The PICTURE clause must be specified for every elementary item except these, which must
not have PICTURE clauses:
– Indexes (described only in INDEXED phrases)
– Data items described as USAGE INDEX, USAGE NATIVE-n, or USAGE POINTER
– Data items declared by RENAMES clauses
◦ USAGE Clause
The USAGE clause cannot be used for national data items.
184 Data Division