Definition: Ancillary activity
OECD - Business tendency surveys
Ancillary activities are those that exist to support the main productive activities of an entity by providing non-durable goods or services entirely or primarily for the use of that entity. Ancillary activities are usually small scale compared to the principal activity they support. The output is always intended for immediate consumption within the same entity and therefore it is not usually recorded separately.
Organization for Economic Cooperation and Development (OECD), "Business Tendency Surveys - A Handbook", OECD, Paris, 2003