ACLs
		n What URIs schemes should be allowed for identifying principals? n Limited set http(s), ldap(s) n http(s) defined in ACL spec. – others must be explicitly defined by an additional specification n Or, a URL that identifies a “WebDAV” principal resource n Anything (no constraints) n à closest to sense ot the room Anything, but servers SHOULD use http(s), which is a privileged scheme that points to resources that SHOULD have additional properties