ESMA published last October "Guidelines on Alternative Performance Measures". The guidelines are applicable for all listed companies and companies drawing up prospectuses when they report alternative performance measures in financial reports and prospectuses. The guidelines come into force on 3 July 2016. The Financial Supervisory Authority of Norway is responsible for monitoring the compliance with the guidelines in the Norwegian market.
Guidelines on Alternative Performance Measures can be found herehttps://www.esma.europa.eu/sites/default/files/library/2015/10/2015-esma-1415en.pdf
See also ESMA's reminder to all listed companies https://www.esma.europa.eu/press-news/esma-news/esma-reminds-issuers-alternative-performance-measures-guidelines-come-force-3