The transfer of securities was taking place in the books of the CSD and the transfer of cash on the accounts of the central bank. This structure resulted from legal provisions, but also contributed to economic efficiency by allowing scale and network effects.
•  The CSD was generally closely connected with the trading, clearing and settlement system in a vertically integrated structure, usually based on common ownership. Services were provided in two layers. The CSD provided clearing, settlement, safekeeping and other services to its settlement members.