# Recommendation S.6 (11/1988): Characteristics of answerback units (ITA2)

> recommendation/international standard from the International Telecommunication Union

**Wikidata**: [Q27051449](https://www.wikidata.org/wiki/Q27051449)  
**Source**: https://4ort.xyz/entity/recommendation-s-6-11-1988-characteristics-of-answerback-units-ita2-