The lexicon of the top500 ( The Encyclopedia for Classification Codes ) explains the codes and definitions in the world of economical classifications.
NACE Code Q Extra-territorial organizations and bodies
The NACE Code Q is described as
Extra-territorial organizations and bodies
Description NOTE: This section allows the employees of extra-territorial organisations to state the activity of their employer in censuses or studies, even though the employer is considered to be outside the economic territory of a country (although within the geographical territory).