Data definitions are the objects used to store all that meaning about the underlying data we talked about. They define the type of data they can hold (using an existing DataType plugin) and any kind of other meaningful information about that data. So, together with the plugins, the data definitions are one mean data modeling machine.
At the lowest level, they implement the DataDefinitionInterface and typically extend the DataDefinition class (or one of its subclasses). Important subclasses of DataDefinition are the ListDefinition and ComplexDefinitionBase which are used to define more complex data types. And as you might expect, they correlate to the ListInterface and ComplexDataInterface plugins I mentioned earlier.
Let ...
