Document Delivery Service (DDS):

Document Delivery Service is actually concerned with the supply of documents to the users on demand, either in original or its copy in print or non-print form, irrespective of the location and form of the original. Most of the other information services such as current awareness service, SDI service, indexing and abstracting services, etc. , are designed mainly  to guide the users to the currently published sources of information, whereas DOS actualy locates the required document and supplies it to the requester. DDS is a very important service, since the value and importance of other access services are directly dependent on the efficiency of this service. For instance, if a user, alerted by a current awareness service, requires a document and efforts are not made to supply the same to him in time, then the availability of any alerting service, however efficient it may be, will have no value for him. Thus, DDS adds value to other information services.