First draft.
+The more a communication system grows and increases its diversity, the more +likely it is that conflicts arise over which content is acceptable and which +is not. In addition, some content may be psychologically triggering or harmful +to different people or age groups, while the same content may be desirable to +share and talk about in other groups.
+ +This specification intends to provide a machine-readable and extensible way of +conveying the kinds and classes of content which are acceptable, and hence to +be expected, on a service. Such a service can be an instant messaging account +server, a &xep0045; service or room, a &xep0369; service or channel or any +other entity which is able to publish extensions as per &xep0128;.
+ +The content ratings are provided as a set of free-form strings, scoped by a +type URI.
+ +This idea is not new. The W3C for instance has had two initiatives revolving +around labelling content for the web. The +Platform for Internet Content Selection (PICS) +has been superseded by the +Protocol for Web Description Resources (POWDER).
+ +While the PICS approach is roughly similar to what this document intends to +achieve, the POWDER standard goes way beyond that and provides much more +extension points, at the cost of higher complexity.
+ +&xep0258; provides a way to embed security labels in contexts where clearance +to view specific content is required. While the rating of content is roughly +similar, the XEP-0258 standard goes beyond that by placing restrictions +on entities which carry such labels in a way which is not desirable for this +standard.
+ +Specifically, the document states that supporting implementations MUST NOT +allow the <securitylabel/> element outside of contexts of specifications +known to them, which could pose interoperability issues if that element was +reused for this specification.
+ +Content Label: +A free-form string qualified by a type URI.
+ +Content Rating: +A set of Content Labels which describe the describes the classes of +content which may be encountered at the entity to which the rating +applies.
+ +The Content Rating is conveyed using a set of free-form strings qualified +by a type attribute, the Content Labels.
+ +A Content Label is represented by a single XML <simple-label/> element +qualified by the urn:xmpp:crl:0 namespace:
+ +The type attribute MUST be a URI. It defines the format of the CDATA +contained in the <simple-label/> element. The character data of the +<simple-label/> element MUST NOT contain control codes (including newline +and horizontal tab).
+ +The type URI must be URL-encoded, escaping all whitespace.
+ +A Content Rating is represented by a <content-rating/> XML element qualified +by the urn:xmpp:crl:0 namespace. It carries zero or more <simple-label/> +child elements as described above.
+ +Future extensions MAY specify other child elements for <content-rating/> in +separate namespaces. See the business rules for an approach for handling those +unexpected elements.
+ +If the format needs to be conveyed in plain text form, for example to carry +the list of labels in &xep0128; or a &xep0004; configuration form, the +following algorithm is to be applied:
+ +An entity may publish a content self-rating using &xep0128;. For this, a +&xep0004; form with the urn:xmpp:crl:0 FORM_TYPE is defined. +All labels are mapped to a single text-multi.
+ +Each line in the text-multi field is prefixed with the key of the +corresponding <simple-label/> element. The key is followed by a single +space character (U+0020), followed by the character data of the +<simple-label/> element.
+ +Entities with sufficient permissions to modify &xep0045; room configuration +SHOULD be offered a text-multi form field of the format described above. If +offered this field MUST be mapped to the format described above in the +&xep0030; response of the room.
+ +Implementations which convert the labels to human-readable strings need to +translate those strings. For now, no provision is made to provide +pre-translated texts.
+ +REQUIRED.
+ +REQUIRED.
+ +REQUIRED.
+ +REQUIRED for protocol specifications.
+