datums property
The different datums used around the world. These contain the ellipsoid that each datum uses and the transform that is used on each latitude and longitude. I'm sure that there are datums that aren't listed here, if you would like a datum included that isn't listed please get in touch with the ellipsoid and transform parameters.
Implementation
final datums = {
"OSGB36":{ "ellipsoid": "Airy1830", "transform": [ -446.448, 125.157, -542.060, 20.4894, -0.1502, -0.2470, -0.8421 ] },
"WGS84":{ "ellipsoid": "WGS84", "transform": [ 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0] },
"ED50": { "ellipsoid": "Intl1924", "transform": [ 89.5, 93.8, 123.1, -1.2, 0.0, 0.0, 0.156 ] },
"ETRS89": { "ellipsoid": "GRS80", "transform": [ 0, 0, 0, 0, 0, 0, 0 ] },
"Irl1975": { "ellipsoid": "AiryModified", "transform": [ -482.530, 130.596, -564.557, -8.150, 1.042, 0.214, 0.631 ] },
"NAD27": { "ellipsoid": "Clarke1866", "transform": [ 8, -160, -176, 0, 0, 0, 0 ] },
"NAD83": { "ellipsoid": "GRS80", "transform": [ 0.9956, -1.9103, -0.5215, -0.00062, 0.025915, 0.009426, 0.011599 ] },
"NTF": { "ellipsoid": "Clarke1880IGN", "transform": [ 168, 60, -320, 0, 0, 0, 0 ] },
"Potsdam": { "ellipsoid": "Bessel1841", "transform": [ -582, -105, -414, -8.3, 1.04, 0.35, -3.08 ] },
"TokyoJapan": { "ellipsoid": "Bessel1841", "transform": [ 148, -507, -685, 0, 0, 0, 0 ] },
"WGS72": { "ellipsoid": "WGS72", "transform": [ 0, 0, -4.5, -0.22, 0, 0, 0.554 ] },
};