{
	"transformations": [
		{
			"from": "EPSG:4267",
			"to": "EPSG:4269",
			"method": "NADCON grid interpolation",
			"accuracy": "15cm - 1m",
			"notes": "Requires NADCON grids. Accuracy varies by location.",
			"epsgCode": "EPSG:1241",
			"reversible": true
		},
		{
			"from": "EPSG:4269",
			"to": "EPSG:6318",
			"method": "Time-dependent Helmert transformation",
			"accuracy": "1-2cm",
			"notes": "NAD83 to NAD83(2011) involves plate motion corrections.",
			"reversible": true
		},
		{
			"from": "EPSG:4269",
			"to": "EPSG:4326",
			"method": "Null transformation",
			"accuracy": "1-2m",
			"notes": "NAD83 and WGS84 are practically identical for most applications. Differences at cm level exist.",
			"reversible": true
		},
		{
			"from": "EPSG:6318",
			"to": "EPSG:4326",
			"method": "Helmert transformation",
			"accuracy": "1-2cm",
			"notes": "NAD83(2011) is closely aligned with ITRF. Transform via ITRF for highest accuracy.",
			"reversible": true
		},
		{
			"from": "EPSG:4269",
			"to": "EPSG:5070",
			"method": "Albers Equal Area Conic projection",
			"accuracy": "Projection accuracy (area preserved)",
			"notes": "Direct projection from NAD83 to Conus Albers.",
			"reversible": true
		},
		{
			"from": "EPSG:6318",
			"to": "EPSG:6350",
			"method": "Albers Equal Area Conic projection",
			"accuracy": "Projection accuracy (area preserved)",
			"notes": "Direct projection from NAD83(2011) to Conus Albers.",
			"reversible": true
		},
		{
			"from": "EPSG:4269",
			"to": "EPSG:3857",
			"method": "Web Mercator projection",
			"accuracy": "Projection accuracy (conformal, high distortion at poles)",
			"notes": "Via WGS84 (null transform) then Web Mercator projection.",
			"reversible": true
		},
		{
			"from": "EPSG:4326",
			"to": "EPSG:3857",
			"method": "Web Mercator projection",
			"accuracy": "Projection accuracy (conformal, high distortion at poles)",
			"notes": "Direct projection to Web Mercator.",
			"reversible": true
		}
	],
	"hubCrs": ["EPSG:4269", "EPSG:6318", "EPSG:4326"],
	"deprecatedCrs": ["EPSG:4267"],
	"migrationPaths": {
		"EPSG:4267": {
			"recommendedTarget": "EPSG:4269",
			"reason": "NAD27 is superseded by NAD83. Use NADCON for transformation.",
			"notes": "NADCON grids required for accurate transformation."
		}
	},
	"datumRelationships": {
		"NAD27_NAD83": {
			"description": "NAD27 to NAD83 transformation",
			"typical_shift": "10-100 meters depending on location",
			"method": "NADCON grid interpolation",
			"considerations": [
				"Shift varies significantly across the US",
				"Maximum differences in Alaska and Hawaii",
				"CONUS shifts typically 10-100m"
			]
		},
		"NAD83_WGS84": {
			"description": "NAD83 and WGS84 are practically identical",
			"typical_shift": "0-2 meters",
			"method": "Null transformation or Helmert",
			"considerations": [
				"For most applications, can be treated as equivalent",
				"For high-precision work, use explicit transformation",
				"Differences due to different reference frames"
			]
		},
		"NAD83_NAD83_2011": {
			"description": "NAD83 to NAD83(2011) modernization",
			"typical_shift": "0-1 meter",
			"method": "Time-dependent transformation",
			"considerations": [
				"Accounts for tectonic plate motion",
				"Required for GNSS-derived positions",
				"Most significant in western US"
			]
		}
	}
}