When the KEY phrase is not specified, the file position indicator is set to the record in the file with a key (relative record number) equal to the RELATIVE KEY data item.
When the KEY phrase is specified, data-name-1 must specify the RELATIVE KEY. The file position indicator is positioned to the first logical record currently existing in the file with a key (relative record number) that satisfies the comparison with the RELATIVE KEY data item.
When the KEY phrase is not specified, KEY IS EQUAL (to the prime record key) is implied.
Data-name-1 may be qualified; it may not be subscripted.
When the START statement is executed, a comparison is made between the current value in the relative key and the relative record numbers of existing records in the file.
If the FILE STATUS clause is specified in the FILE-CONTROL entry, the associated status key is updated when the START statement is executed. (See "Status Key" under Common Processing Facilities.)
Whether or not the KEY phrase is specified, the key data item used in the comparison is the RELATIVE KEY data item. When START statement execution is successful, the file position indicator points to the logical record in the file whose key satisfies the comparison, and this key becomes the reference for subsequent READ statements.
When START statement execution is unsuccessful, the key of reference and the file position indicator are undefined.