HABApp - Basic questions about OpenhabItem

I have some basic question about the usage of OpenhabItem:


    def __init__(self, name: str, initial_value: Any = None,
                 label: Optional[str] = None, tags: FrozenSet[str] = frozenset(), groups: FrozenSet[str] = frozenset(),
                 metadata: Mapping[str, MetaData] = Map()):

In which use cases the constructor is used?

All I have seen is in the form

my_item_val = OpenhabItem.get_item("MyItem").get_value()

The constructor can be used to create an item that is detached from the registry - e.g. for testing (tbd)