A contractual provision of something (a non physical object), by one, for the use of one or more others.
SESAR European ATM Architecture (EATMA) Guidance Material v7 (D138, Ed. 00.07.00, 2016)
Services involve interactions between providers and consumers, which may be performed in a digital form (data exchanges) or through voice communication or written processes and procedures.
Lexicon Release 2015.1