NULL is OK, both for passing and for returning.

Generics and defining elements of containers and arrays.

Parameter for input and for returning results. Default is transfer full.

Parameter for returning results. Default is transfer full.

Out parameter, where caller must allocate storage.

The callback is valid until first called.

Free data container after the code is done.

Alias for transfer none, used for objects with floating refs.

Free data after the code is done.

Don't free data after the code is done.