This property holds the children of this field.
Items in this collection can be referenced by partial field name
or by zero-based index. The type of the value you pass is used to
determine whether you are looking by name or by index.
So if you intend to reference an item by index, pass a number.
If you intend to reference an item by name, pass a string. In cases
where a string is passed but no matching items could be found, an
attempt will be made to convert the string to a number and return
an item with that index.
As with all collections, you can use the Count property to
determine the number of items contained, and you can iterate
through the collection using the standard methods appropriate to
the language you are coding in.