References
You can use references in the layout definition for fixed-length format data.
You can use a reference in the length clause of a zone to specify that the size of the
corresponding table column depends on the length of the data in another zone. You can also use a
reference in a Nullif clause of a zone to specify that the nullness of the corresponding table
column depends on the value of the data in another zone.
The following table shows examples of references.
| Reference | Meaning |
|---|---|
| BYTES &2 | Error only internal @ reference is allowed for length clause (in any format or zone type). |
| BYTES @ | An error length-clause cannot refer itself. |
| NULLIF & = '123' | A self-reference (no number) is valid in the null clause. The length must be BYTES 3 or CHARS 3 for text styles. The references matches (nullif evaluates to 'true') only '123' (a row in the external file that contains '123'). |
| NULLIF && = '123' | The reference matches (nullif evaluates to 'true') '123', ' 123', ' 123 ', if spaces are
skipped. The length must be at least BYTES 3 or BYTES 4 for this literal value. |
| NULLIF @ = 123 | This reference is valid for numeric zones. The reference matches '123', ' 123 ,' and so on, in the text format, with spaces skipped. |
| NULLIF @ = '2000-01-01' | This reference is valid for date zones. |