olemus
kontekstist sõltuv passiivne roll
= a context-dependent passive role

näiteid
ISO 9000:
auditirühma saatev isik, kes ei tegutse audiitorina
= person who accompanies the audit team
but does not act as an auditor

ISO 22300:
ülesandes osaleja, kes
on harjutuse tunnistajaks,
harjutuse tegevustest eraldatuna;
võib osaleda hindamisprotsesis
= participant who witnesses the exercise while remaining separate from exercise activities
Note. Observers can be part of the evaluation process.

ülevaateid
https://en.wikipedia.org/wiki/Observer

https://en.wikipedia.org/wiki/Observer_pattern