Introduction This Part is directed toward Cellular Digital Packet Data (CDPD) Service Providers and manufacturers intending to build equipment for use in the CDPD internal network. This part does not directly impact CDPD subscribers or Mobile End System (M-ES) manufacturers. This Part assumes that the reader is familiar with CDPD in general@ as presented in [IS-732-100]. This Part defines the specific requirements for Directory User Agents (DUAs) and Directory System Agents (DSAs) to be used in the CDPD Network to perform Application Entity Title-to-Presentation Address translation. This Part enumerates the specific features of DUAs and DSAs that may be used for this particular application of Directory Services. General requirements for CDPD DUAs and DSAs are defined in Part 1013. This specification covers the directory function operating in the Application Layer@ which maps application-titles onto presentation-addresses. This function is carried out by use of the Directory if the information required to accomplish the mapping is not conveniently available by other means. Use of Application-Entity Look-up Directory profile is not mandatory but is recommended. The users are CDPD application-entities and the object classes of interest are also application-entities or subclasses thereof. The main attribute type concerned@ other than those for naming@ is the presentation-address. Other attribute types@ not viewed as necessary for the directory function itself@ may support verifying or finding out the application-entity type. or the lists of supported application contexts@ abstract syntaxes@ and so on.