A structure type can contain nested structures or arrays. Structures can be nested up to 25 levels. The overall size of a structure must be less than 2Gbytes. To calculate the size of a structure, you add up the sizes of all the fields in the structure. If the structure contains nested array fields or structure fields, count only the bottom-level fields (integer, float, and string) to determine the structure size. The following table shows the length of a field of each ESL type. This table applies only to fields defined without a using clause.

For information on the lengths of fields defined with using clauses, see the table showing the lengths of fields by type.