Record Description Entry COBOL

A record description entry consists of a set of data description entries that describe the characteristics of a particular record.Each data description entry consists of a level-number followed by a data-name and a series of independent clauses, as required.

{data-description-entry-1 }…

Level-Numbers

The first data description of a record must have a level-number of 01 or 1, and must start in area A of a source line.

Any data item whose description specifies a level-number in the range 01 through 48 may be subdivided into one or more subordinate data items.When this is done, the subdivided data item becomes a group item.The subdivision is accomplished by following the data description of the group item by one or more further data item descriptions, each having the same level-number.The common level-number selected for these immediately subordinate data items must be larger (by one or more) than the level-number of the group data item but less than 50.

Each subordinate data item may in turn be subdivided by the same process, and the nesting of subordinates within subordinates is limited only by the availability of increasing level-numbers that are less than 50. This arrangement of data definitions results in a hierarchical data structure.The rank of the constituent data items is determined by the numerical value of its level-number:the smaller the level-number, the more inclusive the data item and the higher its rank.

Elementary Items

Any data description entry that is not further subdivided is called an elementary item.A record itself may be an elementary item, consisting of a single level-01 data description entry.A subdivided data description entry with its subdivisions is called a group and is nonelementary.Therefore, a group includes all group and elementary items following it until a level-number less than or equal to the level-number of that group is encountered.

Note that certain clauses of the data description entry may occur only in elementary items.They may not occur in a nonelementary entry as they may affect the subdivisions of that entry.The description of an elementary item must have either a PICTURE clause or INDEX usage; it may not have both.


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