CAS and SDI are types of current awareness services that aim to keep users informed of new developments in their fields. CAS disseminates information to all users on a topic, while SDI provides personalized, targeted information to individuals based on their specific interests. SDI involves creating user profiles that are matched to document profiles to select only the most relevant new information for each user. Both services rely on scanning current literature sources, but SDI uses computers to automate the selection and notification process, providing a more precise service than general CAS updates. The goal of both is to save users' time by bringing new relevant information to their attention in a timely manner.

1. Unit : 1
Information Services and
Organisation
Types of Information Services
CAS & SDI
Bhakti J Khatsuriya
Librarian
C.U.Shah Institute of Nursing
C.U.Shah University
Wadhwan City

2. Introduction
Dissemination of information that will
keep it users well-informed and up-todate
in their fields of basic interest as well
as in related subjects is called Current
Awareness Service. It is a system of
getting knowledge on recent
developments which relate to the
special interest of individual

3. CAS is a device of the information system
through which the users of information can
be informed promptly, as soon as possible
after publications but before absorption
into the comprehensive secondary sources
of current literature on a broad subject field
or on a area in which a group of persons
are interested, and presented in a manner,
volume and rhythm intended to facilitate or
cultivate current approach to information.

4. Meaning and Definition
S.R. Ranganathan defines CAS as
"Documentation periodical listing the
documents appearing during the period
covered, and without being selected to
suit the requirements of a particular
reader or of a specific topic under
investigation. It endeavors to keep the
clientele informed promptly of all the
nascent thought created in their fields of
work and related fields.

5. B.C. Vickery define “CAS is more
frequently
and more adequately met by circulation
than by retrieval, current journals, newly
received book and report, abstract
bulletins
and the like being fed to and scanned by
users.
Basically, speaking, CAS is a device for
alerting specialists towards latest
developments and new publications
acquired by the libraries/information
center

6. Types of Current Awareness
Service
Two kinds of Current awareness services may
be recognized
a. Those services, which are directed towards
individuals or group of users. These may include
communication of information to individuals or
groups through informal conversation or via
telephone, message sent on notification form,
SDI, selective of dissemination of documents,
routing of periodicals (or automatic loan ) and
other documents. In this field, information
supplied within the period of one week to one
month -

7. b. Those services, which are directed
towards all users of the services, these
may include accession list ( a list of
recent acquisitions), bibliography,
indexing and abstracting services,
bibliographic surveys, literature surveys,
table of contents of periodicals received
in the library, Current Awareness
bulletin, etc -

8. Aims of CAS
i. To aware the scientists/users with latest
developments in there subject fields.
ii. To keep the clientele well-informed
and up-to-date knowledge of latest
development in their fields of research
iii. To fulfill the current demand of the
users.

9. Characteristics of CAS
i. Visual channel: There is visual channel for
user to know the current developments
through:
a. Information obtained orally from colleagues.
b. Information received/gathered through
the receipt of pre-prints, reprints.
c. Information gathered through attending
meeting and conferences and getting
information in both formal and informal way.

10. ii. Literature channel:
a. Scanning of current issues of periodicals.
b. Regular perusal of abstracting and indexing
periodicals in one’s subject fields.
c. In some cases reviews and monographs are
also consulted.
iii. Formal channel (Current channel):
a. Regular perusal of current issues of
periodicals.
b. Current issues of abstracting and individuals
periodicals.
c. Maintaining profiles (personal files of the
users).

11. iv. A CAS is an announcement mechanism
usually in documentary form.
v. Record of answer of any specific query as
current approach to information like a
panoramic view of current development.
vi. A CAS is mainly addressed to those
workers who cannot depend entirely on
their own informal channels.
vii. Speed and timeliness is the essence of
CAS.
viii. Due to the very nature of current
approach, ease of scanning has to be
ensured in a Current Awareness bulletin.

12. Factors Influencing on CAS
1. Current Approach: It is necessary for
every informatory to keep himself known with
the current literature or the latest
development of subject. He must know all
the important areas as soon as published or
generated.
2. Continuous need: CAS is very much
required where there is continuous need of
current affairs and developments by the
user. More continuous need, more Current
Awareness service.

13. 3. Direct demand: For many issues the
user may not be immediately interested
but some of the reference may be
demanded by him at any moment. For
such needs some of the references are
recorded in his diary or personal file kept
with the library or informator, so that
when to need arises they may be supplied
with latest developments.

14. Selective Dissemination of
Information
SDI is a type of current awareness service
meant to keep the user abreast with the latest
developments in the field of his interest. It is a
personalized service meant for the individual or
a group of users having identical information
needs. It is a quick service which provides the
pinpointed and exhaustive information to the
users. SDI involves the screening of the
document and selecting the information
according to the specific information needs of
each user or group of users (homogeneous).
The main objective is to keep the user well informed
and up-to-date in his area of interest.

15. Meaning and Definition
Selective Dissemination of Information (SDI)
is defined as the system in which selectively
and automatically compiled information
about new documents is disseminated to
researchers, scientists and others who need
these documents/information or supplying
each user or group of users with a
reference of documents or abstracts
relating to their predefined areas of interest.
It involves notifying the material that
matches the interests of the client.

16. •Selective Dissemination of Information was a
concept first described by H.P. Luhn for the
scientist /engineers of IBM. According to him,
"The Selected Dissemination of Information is
the service within an organization which
concerns itself with the channeling of new
items of information, from whatever sources, to
those points within the organization where the
probability of usefulness in connection with
current work or interest in high. On the other
hand, the service endeavors to withhold such
information from the points where the
probability is low”

17. Objectives of SDI
To provide current information on a
predefined area of interest.
To receive, scan and provide the
literature / information to the right users at the
right time.
All the current information which is
relevant to the interest of the user must
be brought to the notice of the user notification

18. All the relevant information which is
published elsewhere in the world (in
English or other languages) should be
located through various sources.
To achieve current requirements through
the scan of current material such as
journals, current awareness bulletins and
other important resources.
To save the time of the user.
No irrelevant documents should be
brought to the notice of the user. Only
the selective and relevant documents
should be brought to the notice of the
user.

19. Characteristics of SDI
It is a computerized assisted service.
SDI is concerned with current published
information.
The source of current information may be available
both within the organization and outside it.
The new / current information should be
disseminated to the users such as researchers,
scientists, managers, etc. within the organization.

20. The channeling or directing of this
information depends upon the nature of
this interest.
One of the important things in SDI service
is that only current and selective
information which is highly relevant to
the user's interest is to be selected by the
computer for dissemination.

21. Difference Between CAS & SDI
SDI is a form of CAS. The objectives of both
services is to keep the users well-informed and
up-to-date in their field of research. CAS is the
awareness service. It makes the user aware of
the current developments that are taking
place in his area of interest. Whereas SDI deals
with providing the exact or pinpointed
information. It is not possible to state the exact
information in case of CAS, whereas it
necessary to state the exact information need
of the user in SDI. SDI is an advance type of
current awareness service which is directed
towards the individuals.

22. Both the services are based on availability of
current literature. SDI is a personalized service and
is directed towards the individuals or homogeneous
group, whereas CAS is awareness service which is
directed towards all the users who need it. CAS is
provided by
circulating the current list of periodicals among all
the users, whereas SDI service is based on
matching the user's profile with the document
profile. SDI is a selective service based on the exact
information need of the user, whereas in CAS all the
information is
circulated to the user on the given topic. CAS can be
provided without computer, whereas SDI is a
computerized service. Feedback is an important
step is providing SDI service, whereas that is not
required in CAS.

23. Conclusion
CAS and SDI are the very important
information sources for researchers and
other aspirants who want up-to-date
information due to the emergence of
Internet and other wed based
applications these two services are
providable through fingertips.