Note | The value may be a unique identifier from a database, or any other externally-defined string identifying the referent. No particular syntax is proposed for the values of the key attribute, since its form will depend entirely on practice within a given project. For the same reason, this attribute is not recommended in data interchange, since there is no way of ensuring that the values used by one project are distinct from those used by another. In such a situation, a preferable approach for magic tokens which follows standard practice on the Web is to use a ref attribute whose value is a tag URI as defined in RFC 4151. |