An alias name provides an alternative name to an object. For example, the alias 'Jack' may point to the object with the RDN 'John Smith'. An object can have no alias or one or more aliases. Apart from providing user-friendly alternative names, aliases are also useful in providing distribution lists. For example, the alias entry 'Coffee Club' may point to all objects which are members of the Coffee Club.

Similarly, sub-trees of aliases can also be used, say in the definition of Yellow Pages (business categories) from the White Pages of a telephone directory. This offers an alternative to filtering, which can be expensive in some cases.

Naming Authorities.

A naming authority is an authority responsible for the allocation of names. Naming authorities can be countries, companies, departments etc.

According to the definition of DNs and RDNs, it is obvious that there has to be some kind of management and authority at every level of the DIT to ensure that the names assigned are unambiguous at the immediatly succeeding levels. At the corporate level, the corporation and the departments may be the naming authorities. For an isolated corporate directory, this will be sufficient.

However, if the directory has to inter-connect and be accessible on a global basis, the corporation needs to register with the national (and through them, the international) naming authorities.

Various registration authorities have been defined such as ISO, Ansi etc. As the DNs are hierarchical in structure, the registration authorities are also structured in a hierarchical manner. The procedures for registering DNs have not been finalised. However, it is expected that ISO will be the top naming authority overall, followed by the naming authority from each country. For different countries, there may then be further subdivisions such as state and regional naming authorities, if deemed necessary.

For example, within the US, Ansi will act as the top-level US registration authority. Corporations will then have to register the company's RDN with Ansi, which is also likely to register location names (eg states and territories).

Within the UK, the naming authority is expected to be the British Standards Institute (BSI) and the UK companies will have to apply to the BSI to register their names.