To create a project-specific data type, a technical developer must first declare the new type in the type.xml file.

The declaration consists of the following components:

Shown below is a sample definition of a type:

The id is the name of the type. The type id must be unique.

impClass defines the implementation class of the type. For a simple type that has only one property, the implementation class is com.ibm.btt.base.DataField. For a compound type that has multiple properties, the implementation class is com.ibm.dse.base.KeyedCollection or com.ibm.btt.base.IndexedCollection.

The property descriptor specifies the default business rules and behavior for a data type. A property descriptor can have one validator, which is used to check instance data, and one or multiple converters, which are used to transform instance data into a different format. A simple type has only one property descriptor. A compound type has multiple property descriptors.

In most cases, a technical developer does not need to implement their own property descriptor class. UDTT provides the SimplePropertyDescriptor property descriptor class for simple types, KCollPropertyDescriptor and ICollPropertyDescriptor for compound types, and StringDescriptor, IntegerDescriptor, FloatDescriptor, and DateDescriptor for basic types. A technical developer can also implement their own property descriptor by extending AbstractPropertyDescriptor, which is the parent property descriptor class for all property descriptors.