The lexicon of the top500 ( The Encyclopedia for Classification Codes ) explains the codes and definitions in the world of economical classifications.
ISIC Code Q Extra-territorial organizations and bodies
The ISIC Code Q is described as
Extra-territorial organizations and bodies
Description This section allows the employees of extraterritorial organizations 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).