Mapping repeating structures is slightly different from mapping single elements because of the nature of the elements or instances that are available for mapping. The following example shows a message tree node partially expanded.
message1 |_ top |_ middle[] |_bottom[] |_ middle[1] |_bottom[] |_bottom[All] |_bottom[1]
In this example, an entry followed by [] is referred to as a repeatable node, one followed by [All] is referred to as an all node, and one followed by [1] is referred to as an instance element node.
There are two ways to create a mapping to a non repeatable (scalar) target for some form of aggregation: