CPV code 98910000 designates Services specific to international organisations and bodies in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
98910000 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 98900000 (Services provided by extra-territorial organisations and bodies).