The six-month migration process went smoothly and did not cause any operational disruptions. Slovakia joined TARGET2 on 1 January 2009, Bulgaria joined in February 2010, and Romania joined on 4 July 2011. The objectives of TARGET2 are to:  The use of TARGET2 is mandatory for the settlement of any euro operations involving the Eurosystem. The Eurosystem consists of the European Central Bank (ECB) and the national central banks of the 19 European Union member states that are part of the Eurozone. Participation in TARGET2 is mandatory for new member states joining the Eurozone. TARGET2 services in euro are available to non-Eurozone states. National central banks of states which have not yet adopted the euro can also participate in TARGET2 to facilitate the settlement of transactions in euro. Central banks from five non-Eurozone states Croatia, Bulgaria, Denmark, Poland and Romania also participate in TARGET2. In 2012, TARGET2 had 999 direct participants, 3,386 indirect participants and 13,313 correspondents. TARGET2 is the real-time gross settlement (RTGS) system with payment transactions being settled one by one on a continuous basis in central bank money with immediate finality. There is no upper or lower limit on the value of payments. TARGET2 mainly settles operations of monetary policy and money market operations. TARGET2 has to be used for all payments involving the Eurosystem, as well as for the settlement of operations of all large-value net settlement systems and securities settlement systems handling the euro. TARGET2 is operated on a single technical platform. The business relationships are established between the TARGET2 users and their national central bank. In terms of the value processed, TARGET2 is one of the largest payment systems in the world. TARGET2 is a harmonised RTGS system covering the Eurozone. It operates on the Single Shared Platform (SSP), which replaced the decentralised first-generation TARGET system. It was designed to provide an enhanced service with benefits for economies of scale which allows it to charge lower fees and offer cost-efficiency. All participants of the Eurosystem, and outside it, can access the same functionalities and interfaces, as well as a single price structure. SWIFT standards and services (i.e. FIN, InterAct, FileAct and Browse) are used in the harmonised communication between the system and its participants. Before the introduction of TARGET2, some central banks held "home accounts" (also called "proprietary home accounting systems") outside their RTGS systems.