The official list of all top-level domains is maintained by the Internet Assigned Numbers Authority (IANA). IANA also oversees the approval process for new proposed top-level domains. As of January 2016, the root domain contains 1205 top-level domains, while a few have been retired and are no longer functional.
As of 2015, IANA distinguishes the following groups of top-level domains:
At a lower level of organization, infantry units commonly incorporate organic armour or artillery units to improve their combined arms capability. Organic assets are closely integrated into their parent unit's command structure and their personnel are familiar with other personnel in the parent unit, improving coordination and responsiveness and making the parent unit more self-sufficient.
However, over-emphasis of organic assets can create wasteful redundancy. For instance, an infantry unit assigned to urban peacekeeping duties might have little use for its organic artillery, while another unit deployed elsewhere might have less artillery support than it required. The question of how much to emphasise the use of organic assets, as opposed to coordination with separate units ('joint organization') is a subject of debate and heavily dependent on questions of command and control.