{
	"version": "1.0.0",
	"symptoms": {
		"coordinate_shift_large": {
			"description": "Coordinates shifted by hundreds of meters to kilometers",
			"keywords": [
				"hundreds of meters",
				"kilometers",
				"completely wrong",
				"large shift",
				"400m",
				"several hundred meters"
			],
			"possibleCauses": [
				{
					"likelihood": "high",
					"cause": "Datum mix-up (Tokyo Datum vs JGD/WGS84)",
					"description": "There is a systematic shift of approximately 400m between Tokyo Datum and JGD2011/WGS84",
					"indicators": [
						"Data created before 2002",
						"Digitized from old maps or drawings",
						"CRS information is unknown or not set"
					]
				},
				{
					"likelihood": "medium",
					"cause": "Incorrect CRS assignment",
					"description": "Data's CRS information is set to a different value than the actual CRS",
					"indicators": [
						"CRS was manually specified during import",
						".prj file is missing or incorrect",
						"Post-transformation CRS is set without actual transformation"
					]
				},
				{
					"likelihood": "low",
					"cause": "Axis swap (X/Y, longitude/latitude)",
					"description": "Longitude and latitude are swapped, or X/Y order is reversed",
					"indicators": [
						"Points appear in the ocean or foreign countries",
						"Coordinate value ranges differ from expectations"
					]
				}
			],
			"diagnosticSteps": [
				{
					"step": 1,
					"action": "Check the data's CRS information",
					"expected": "A clear EPSG code is set",
					"ifFailed": "If CRS is unknown, investigate data origin"
				},
				{
					"step": 2,
					"action": "Check coordinate value ranges",
					"expected": "For Japan: latitude 20-46°, longitude 122-154°",
					"ifFailed": "If values are abnormal, suspect axis swap"
				},
				{
					"step": 3,
					"action": "Compare coordinates of known points",
					"expected": "Matches reference data",
					"ifFailed": "Estimate cause from shift pattern (direction, distance)"
				}
			],
			"solutions": [
				{
					"forCause": "Datum mix-up (Tokyo Datum vs JGD/WGS84)",
					"steps": [
						"Confirm data is in Tokyo Datum",
						"Perform transformation from EPSG:4301 to EPSG:6668",
						"Verify transformed data"
					],
					"prevention": "Document datum when creating data, transform old data before use",
					"tools": ["QGIS", "GDAL ogr2ogr", "PostGIS ST_Transform"]
				},
				{
					"forCause": "Incorrect CRS assignment",
					"steps": [
						"Identify the correct CRS",
						"Correct CRS information (change definition, not transform)",
						"Verify corrected data"
					],
					"prevention": "Always verify CRS information when obtaining data and document it"
				}
			],
			"relatedBestPractices": ["historical_data", "data_exchange"]
		},
		"coordinate_shift_medium": {
			"description": "Coordinates shifted by 1 to several meters",
			"keywords": [
				"several m",
				"1-2m",
				"meter scale",
				"1m",
				"2m",
				"a few meters",
				"off by",
				"meters",
				"1-2 meters",
				"couple meters"
			],
			"possibleCauses": [
				{
					"likelihood": "high",
					"cause": "Tokyo Datum to JGD2011 transformation accuracy",
					"description": "Tokyo Datum → JGD2011 transformation accuracy is limited to 1-2m",
					"indicators": ["Transformation from Tokyo Datum was performed", "Using old data"]
				},
				{
					"likelihood": "medium",
					"cause": "Different transformation parameters",
					"description": "Same transformation can produce different results depending on parameters used",
					"indicators": ["Results differ between software", "Transformation method not documented"]
				}
			],
			"diagnosticSteps": [
				{
					"step": 1,
					"action": "Check transformation history",
					"expected": "Transformation method and parameters are recorded",
					"ifFailed": "If transformation is unclear, verify original data"
				},
				{
					"step": 2,
					"action": "Verify transformation accuracy limits",
					"expected": "1-2m shift is normal for Tokyo→JGD transformation",
					"ifFailed": "If shift is larger, investigate other causes"
				}
			],
			"solutions": [
				{
					"forCause": "Tokyo Datum to JGD2011 transformation accuracy",
					"steps": [
						"Accept 1-2m shift as transformation accuracy limit",
						"Consider re-surveying original data if higher accuracy needed",
						"Record transformation accuracy in metadata"
					],
					"prevention": "Verify data precision requirements and transformation accuracy limits beforehand"
				}
			],
			"relatedBestPractices": ["historical_data", "precision_requirements"]
		},
		"coordinate_shift_small": {
			"description": "Coordinates shifted by centimeters to tens of centimeters",
			"keywords": ["few cm", "centimeters", "minor", "cm", "tens of cm"],
			"possibleCauses": [
				{
					"likelihood": "high",
					"cause": "Difference between WGS84 and JGD2011",
					"description": "WGS84 and JGD2011 are practically identical but strictly differ by a few cm",
					"indicators": [
						"Mixed use of GPS(WGS84) and JGD2011 data",
						"Using high-precision survey data"
					]
				},
				{
					"likelihood": "medium",
					"cause": "Crustal deformation correction from JGD2000 to JGD2011",
					"description": "Coordinates changed due to crustal deformation from the 2011 Tohoku earthquake",
					"indicators": ["Using JGD2000 data from before 2011", "Data from Tohoku region"]
				},
				{
					"likelihood": "low",
					"cause": "Numerical precision/rounding errors",
					"description": "Insufficient decimal places in coordinates or rounding errors during calculations",
					"indicators": ["Coordinates stored in FLOAT type", "Multiple transformations performed"]
				}
			],
			"diagnosticSteps": [
				{
					"step": 1,
					"action": "Check the CRS being used",
					"expected": "Verify WGS84 and JGD2011 are not mixed",
					"ifFailed": "Consider unifying if mixed"
				},
				{
					"step": 2,
					"action": "Check numeric type",
					"expected": "DOUBLE type or DECIMAL type with sufficient precision",
					"ifFailed": "Consider type change if FLOAT type"
				}
			],
			"solutions": [
				{
					"forCause": "Difference between WGS84 and JGD2011",
					"steps": [
						"Use as-is if no practical issues",
						"Unify to one if strict consistency needed",
						"JGD2011 recommended for data within Japan"
					],
					"prevention": "Unify CRS at project start"
				}
			],
			"relatedBestPractices": ["coordinate_storage", "precision_requirements"]
		},
		"area_distance_error": {
			"description": "Area or distance calculations are incorrect",
			"keywords": ["area", "distance", "calculation result", "length", "size", "calculation wrong"],
			"possibleCauses": [
				{
					"likelihood": "high",
					"cause": "Calculations in Web Mercator (EPSG:3857)",
					"description": "Web Mercator has significant area/distance distortion at high latitudes",
					"indicators": ["Using web map library", "Calculating in EPSG:3857", "High-latitude data"]
				},
				{
					"likelihood": "medium",
					"cause": "Planar calculations in geographic CRS",
					"description": "Calculating distance or area directly with latitude/longitude",
					"indicators": [
						"Using degree-unit coordinates directly in calculations",
						"Distance calculation using Pythagorean theorem"
					]
				}
			],
			"diagnosticSteps": [
				{
					"step": 1,
					"action": "Check the CRS used for calculations",
					"expected": "Appropriate projected CRS (Japan Plane Rectangular CS for Japan)",
					"ifFailed": "Transformation needed if Web Mercator or geographic CRS"
				},
				{
					"step": 2,
					"action": "Calculate expected error",
					"expected": "Web Mercator at 35° latitude: approximately 23% area distortion",
					"ifFailed": "Check if error matches expectations"
				}
			],
			"solutions": [
				{
					"forCause": "Calculations in Web Mercator (EPSG:3857)",
					"steps": [
						"Transform to JGD2011 Plane Rectangular CS before calculation",
						"Or use spherical calculation formulas (Haversine, etc.)",
						"Consider equal-area projection for area calculations"
					],
					"prevention": "Do not use Web Mercator for area/distance calculations",
					"tools": ["PostGIS ST_Area(geography)", "Turf.js"]
				}
			],
			"relatedBestPractices": ["web_mapping", "projection_selection"]
		},
		"display_blank": {
			"description": "Data not displayed or appears blank",
			"keywords": ["not displayed", "blank", "invisible", "disappeared", "nothing shows"],
			"possibleCauses": [
				{
					"likelihood": "high",
					"cause": "Out of coordinate range due to CRS mismatch",
					"description": "Attempting to display data with different CRS in the same view",
					"indicators": ["Only some layers are not displayed", "Blank areas when zooming"]
				},
				{
					"likelihood": "medium",
					"cause": "Coordinate value magnitude mismatch",
					"description": "Mixing meter units and degree units, or unit system errors",
					"indicators": [
						"Coordinate values are extremely large or small",
						"Mixing projected and geographic CRS"
					]
				}
			],
			"diagnosticSteps": [
				{
					"step": 1,
					"action": "Check CRS of each layer",
					"expected": "Same CRS for all layers, or transformable",
					"ifFailed": "Unify CRS or verify transformation settings"
				},
				{
					"step": 2,
					"action": "Check coordinate value ranges",
					"expected": "Within expected range (Japan lat/lon, etc.)",
					"ifFailed": "Data verification needed if values are abnormal"
				}
			],
			"solutions": [
				{
					"forCause": "Out of coordinate range due to CRS mismatch",
					"steps": [
						"Check project CRS",
						"Check and unify all layer CRS",
						"Verify on-the-fly transformation is enabled"
					],
					"prevention": "Check CRS before adding data"
				}
			],
			"relatedBestPractices": ["gis_integration", "data_exchange"]
		},
		"transformation_error": {
			"description": "Error occurs during coordinate transformation",
			"keywords": [
				"cannot transform",
				"error",
				"failed",
				"transformation failed",
				"transform error"
			],
			"possibleCauses": [
				{
					"likelihood": "high",
					"cause": "Transformation parameters not found",
					"description": "Transformation parameters for specified CRS pair are not registered in software",
					"indicators": [
						"Transformation between minor CRS",
						"\"Transformation method not found\" error"
					]
				},
				{
					"likelihood": "medium",
					"cause": "Invalid CRS code",
					"description": "Non-existent or deprecated EPSG code specified",
					"indicators": ["\"CRS not found\" error", "CRS code was manually entered"]
				}
			],
			"diagnosticSteps": [
				{
					"step": 1,
					"action": "Verify CRS code validity",
					"expected": "Code exists in EPSG Registry",
					"ifFailed": "Research correct code"
				},
				{
					"step": 2,
					"action": "Try transformation via intermediate CRS",
					"expected": "Transformation possible via WGS84 (EPSG:4326)",
					"ifFailed": "Manually set parameters"
				}
			],
			"solutions": [
				{
					"forCause": "Transformation parameters not found",
					"steps": [
						"Try two-step transformation via WGS84 (EPSG:4326)",
						"Update PROJ or GDAL version",
						"Manually set transformation parameters"
					],
					"prevention": "Use major CRS, avoid specialized CRS",
					"tools": ["PROJ", "GDAL", "epsg.io"]
				}
			],
			"relatedBestPractices": ["data_exchange", "cross_border"]
		}
	},
	"keywordMapping": {
		"shift": ["coordinate_shift_large", "coordinate_shift_medium", "coordinate_shift_small"],
		"offset": ["coordinate_shift_large", "coordinate_shift_medium", "coordinate_shift_small"],
		"misalignment": ["coordinate_shift_large", "coordinate_shift_medium", "coordinate_shift_small"],
		"off by": ["coordinate_shift_large", "coordinate_shift_medium", "coordinate_shift_small"],
		"off": ["coordinate_shift_large", "coordinate_shift_medium", "coordinate_shift_small"],
		"400m": ["coordinate_shift_large"],
		"hundreds": ["coordinate_shift_large"],
		"kilometers": ["coordinate_shift_large"],
		"1-2m": ["coordinate_shift_medium"],
		"1-2 meters": ["coordinate_shift_medium"],
		"several meters": ["coordinate_shift_medium"],
		"few meters": ["coordinate_shift_medium"],
		"meters": ["coordinate_shift_medium"],
		"couple meters": ["coordinate_shift_medium"],
		"few cm": ["coordinate_shift_small"],
		"centimeters": ["coordinate_shift_small"],
		"minor": ["coordinate_shift_small"],
		"area": ["area_distance_error"],
		"distance": ["area_distance_error"],
		"length": ["area_distance_error"],
		"calculation": ["area_distance_error"],
		"not displayed": ["display_blank"],
		"blank": ["display_blank"],
		"invisible": ["display_blank"],
		"disappeared": ["display_blank"],
		"cannot transform": ["transformation_error"],
		"error": ["transformation_error"],
		"failed": ["transformation_error"]
	}
}