Defining a repeating group Schema DDL
66 U929-J-Z125-9-76
4.4 Defining a repeating group [level-number-1 ]group-item-name OCCURS integer TIMES.
⎧ ⎧PICTURE.....⎫ ⎫
⎨level-number-2 record-element-name[ ⎨ ⎬][ OCCURS.....].⎬...
⎩ ⎩TYPE..... ⎭ ⎭
A group item is a named grouping of record elements within a record type. A record element
can in this case be either an item, a vector or even a group item.
A repeating group is a group item with repetition factor. The repetition factor must be greater
than 1. It defines how many duplicates of a group item the repeating group comp rises.
The definition of group items that are not repeating groups is only useful for subschemata
and is therefore not possible using the schema DDL.
group-item-name specifies the user-assigned name of the repeating group.
integer denotes the repetition factor.
record-element-name specifies the record element that is to become part of the repeating
group. It must be defined as described on page 55 if it is an item, as descri bed on page 65
if it is a vector or as described on this page if it is a re peating group.
level-number-2 must be greater than level-number-1.
The following applies for all record elements that are to become par t of a repeating group:
Record elements must have the same level number if they have the next higher repeating
group in common.
A hierarchy of repeating groups may not exceed three levels.
If one record element is a vector, only two more hierarchy levels are allowed.
The limit is the maximum record length.
If you want to use elementary items of a repeating group as key items, you must bear in
mind that in each case the first variant of the higher-ranking re peating group is taken as a
basis and that this may be continued recursively up to the outer repeating group.