The United Nations and the specialized agencies often call upon experts on individual contracts to work on short-term projects in their area of expertise. A special service agreement (SSA) is a contractual arrangement within the United Nations system that establishes a legal relationship between the organization and the person in whom the person is an entrepreneur or service provider and not a collaborator. This modality is often used for very short contracts when the organization does not want to take on the burden of the complex bureaucracy of hiring new staff and deal with complex requirements and benefits. Consultations typically include analyzing problems, managing seminars and trainings, preparing documents for conferences and meetings, or writing reports. Many United Nations organizations often use local consultants for service and support functions. A staff service contract is a contract of employment in a United Nations organization that is not governed by the Statute and Rules of the United Nations.  A PSA and an SSA are not personnel contracts. An initial appointment from the SPA is usually valid for a period of one year with the possibility of a temporary and continuous extension; however, the total designation may not exceed six years.