Templates for the unlabeled and netif host types specify a default label. This label is used to control communications with hosts whose operating systems are not aware of labels, such as Oracle Solaris systems. The default label that is assigned reflects the level of trust that is appropriate for the host and its users.
Because communications with unlabeled hosts are essentially limited to the default label, these hosts are also referred to as single-label hosts. A technical reason to call these hosts “single-label” is that these hosts do not have admin_high and admin_low labels.