Wind generation forecasts and actual outturn can be categorised into four groups:  metered onshore, metered offshore, unmetered onshore, unmetered onshore.  For the 'Legacy' wind forecast data ('Wind Forecast Out-turn' and 'Peak Wind Generation Forecast') on the 'Generation' section of BMRS, only the metered wind categories are included (offshore and onshore) and there is a link on the page to the 'Power Park Modules' spreadsheet which gives an exact breakdown of which BMU's are included in the metered forecasts which appear on this page.  There are also explanatory notes within the sheet which clarify the BMU's included for OC2 forecasts as well as 'Legacy' wind forecast data.

For the European Transparency Regulation 543/2013 (ETR) generation forecasts, these are divided into onshore and offshore, and both the metered and unmetered windfarms are included.  For outturn values, latest forecasts are used in place of actual metered output for the unmetered wind as allowed for by the regulation.  For this reason, the wind forecasts for the ETR data (B1620/1630) will differ from the 'Legacy' wind forecast data.