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 callee must allocate storage.

The callback is valid until first called.

The caller owns the data container, but not the data inside it.

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

The caller owns the data, and is responsible for free it.

The data is owned by the callee, which is responsible of freeing it.