Description

why occurs clause cannot be at 01 level ?

**Why Occurs Clause Cannot Be at 01 Level?**

In COBOL programming, it is not possible to use an OCCURS clause at the 01 level. The OCCURS clause is used to define arrays or tables, allowing a data item to be repeated a specified number of times. This is particularly useful for handling collections of similar items. However, according to the COBOL standard, the OCCURS clause cannot be specified in a data description entry that has a level number of 01, 66, 77, or 88.

The question is, why is this restriction in place? The main reason behind this is that the 01 level is a group level, and as such, it does not require any occurrences. Any attempt to use an OCCURS clause at this level would be redundant and unnecessary.

However, there are some nuances to this rule. While it is not possible to use an OCCURS clause at the 01 level, it is possible to use it at lower levels, such as the 02 level. This is because the OCCURS clause is used to define the number of occurrences of a data item, and the 02 level is a child of the 01 level, meaning that it is a subordinate of the 01 level.

In addition, there are some cases where the OCCURS clause can be used at the 01 level, but only if it is used in conjunction with a redefined data item. In this case, the OCCURS clause is used to redefine the data item, and it is not considered to be at the 01 level.

In summary, the OCCURS clause cannot be used at the 01 level in COBOL programming because the 01 level is a group level, and as such, it does not require any occurrences. While it is possible to use the OCCURS clause at lower levels, such as the 02 level, there are some nuances to this rule, and it is not possible to use it at the 01 level without incurring a redundancy.