Why num_temp_instances is set to 0 in map_instance_bank?

[drilistbox]

        map_instance_bank=dict(
            type="InstanceBank",
            num_anchor=100,
            embed_dims=embed_dims,
            anchor=anchor_paths["map"],
            anchor_handler=dict(type="SparsePoint3DKeyPointsGenerator"),
            **num_temp_instances=0** if temporal_map else -1,
            confidence_decay=0.6,
            feat_grad=True,
        ),