From real survey data to clear project delivery.
Great Britain, Northern Ireland, mapping system and height datum remain separate. Survey Control does not silently assume one reference for the whole United Kingdom.
One United Kingdom, multiple survey contexts.
OSGB36/British National Grid belongs to England, Scotland and Wales. Northern Ireland uses ETRS89/Irish Transverse Mercator. Area selection therefore comes before coordinate or height processing.
Great Britain or Northern Ireland
Area, CRS, axis order, unit and source authority each receive an explicit project status. British National Grid is never assumed for the whole UK.
Separate ODN and other datums
Ordnance Datum Newlyn is relevant to mainland Great Britain, while Northern Ireland and islands may have other height contexts. A Z value alone proves no datum.
Evidence the model and version
A conversion between GNSS/ETRS89, British National Grid and heights requires the appropriate transformation context, such as OSTN15/OSGM15 where applicable.
Important. No automatic compliance promise: release requires confirmed area logic, datums, models and project evidence.