12. April 1998

• Position: 

OSGB36 - British National Grid 
Ellipsoid: Airy 1830
Map Projection: Transverse Mercator of Great Britain
Central Point/Datum: da-name

OSGB(SN) 77 - (Scientific Network) 
Ellipsoid: ell-name
Map Projection: prj-name
Central Point/Datum: da-name

OSGB(SN) 80 - (Scientific Network) 
Ellipsoid: ell-name
Map Projection: prj-name
Central Point/Datum: da-name

OSGRS80 
Ellipsoid: GRS80
Map Projection: prj-name
Central Point/Datum: da-name

• Height: 

Name Reference Point: ref_pnt
Reference Level: ref_level
Geoid: geoid-name