Corporates / Companies which issue any kind of security are known as 'Issuer' in the depository system. Only those securities, which are admitted into the CDSL system are available for dematerialisation to the holders of such securities or can be allotted in electronic record form by the issuer. Securities include shares, debentures, bonds, commercial paper (C.P.), certificate of deposits (C.D.), pass through certificates (PTCs), government securities and mutual fund units. Both listed and unlisted securities can be admitted into the CDSL system. CDSL functions as the central accounting and record keeping office in respect of the securities admitted by issuer companies.

It is however desirable that all securities are admitted on both the depositories so that investors having account with any of the depositories can acquire that security.

Before the admission of any security into the CDSL system, it is necessary for the issuer to establish an electronic connectivity with CDSL either directly or through a registrar and transfer agent (RTA), who has already established connectivity with CDSL. All leading RTAs have already established electronic connectivity with CDSL. The procedure and CDSL charges to obtain direct connectivity by an issuer are similar to that as for a RTA. It may please be noted that SEBI, vide its circular dated 27-12-2002, has advised issuers that "all the work related to share registry in terms of both physical and electronic should be maintained at a single point i.e either in-house by the company or by a SEBI registered R & T Agent".

At CDSL, data is centrally stored with state-of-the-art systems and having a 'Disaster Recovery Site' facility as back up. The centralised database architecture of CDSL places it in a unique position to provide issuers up-to-the-moment details of holdings of the security.