Constant REQUIRES_HOST_PREFIX 

pub const REQUIRES_HOST_PREFIX: &'static str;

Prefix of the ActionContract::tags entries naming a capability of the host the action needs: requires-host:native-paths. On a host without it the action is published unavailable, coded HOST_UNSUPPORTED_CODE, and so refused, wherever it is offered: an app declares what its action needs once instead of hiding it per host. A requirement the host does not know is one it lacks.