For this purpose, Constroid forces the developer to dene
an XML le called Datastructures.xml. It is similar to the
AndroidManifest.xml le which must be for every
application. In this the developer how he intents to structure the application data. A at and recursive structure as sketched in Figure 4 is used. consists of a structure which consists of single data items
or other structures. So, data structures are templates for
data instances and consist of at least one data item and zero,
one, or more substructures. Data items are the smallest elements of an data object and are assigned a name and type.
Figure 4 shows the of a contact structure which itself contains an address structure.