Output Reference

Output Reference

CS Extract produces two output files: a flat CSV and a nested JSON document. Both contain the same data, differing only in how the AdditionalInformation field is represented.

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Output Files

File	Format	Encoding
coordinate_systems_extended.csv	RFC 4180 CSV with header row	UTF-8
coordinate_systems_extended.json	JSON array of objects	UTF-8, 2-space indent

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Field Schema

Each record corresponds to one ProjectedCoordinateSystem or GeographicCoordinateSystem element found in the source XML.

#	Field	CSV Column	JSON Key	Type	Description
1	CS_Category	CS_Category	CS_Category	string	The coordinate system type. One of: ProjectedCoordinateSystem or GeographicCoordinateSystem.
2	Human_Readable_Name	Human_Readable_Name	Human_Readable_Name	string	The display name from the <Name> element (e.g., "NAD83 / UTM zone 18N"). Empty string if absent.
3	Description	Description	Description	string	Full description text from the <Description> element. Empty string if absent.
4	Authority	Authority	Authority	string	The raw authority reference string from the <Authority> element (e.g., "EPSG:26918 OGP"). Empty string if absent.
5	EPSG_Code	EPSG_Code	EPSG_Code	string	The EPSG identifier extracted from the Authority text. Parsed by finding the first whitespace-delimited token starting with EPSG: (e.g., "EPSG:26918"). Empty string if no EPSG token is found.
6	Units	Units	Units	string	Unit of measure from the uom attribute of the <Axis> element (e.g., "METER", "DEGREE"). Empty string if the element or attribute is absent.
7	DatumId	DatumId	DatumId	string	The datum identifier from the <DatumId> element (e.g., "NAD83"). Empty string if absent.
8	AdditionalInformation	AdditionalInformation	AdditionalInformation	see below	Key-value pairs from <AdditionalInformation>/<ParameterItem> elements.

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AdditionalInformation Detail

The AdditionalInformation field collects all <ParameterItem> children found under the <AdditionalInformation> element of each coordinate system. Each item has a <Key> and either an <IntegerValue> or <Value> child.

Representation by format

Format	Representation	Example
CSV	JSON-serialized string (escaped and quoted within the CSV cell)	"{""EPSG Code"": ""26918"", ""Projection"": ""Transverse Mercator""}"
JSON	Native JSON object (nested dictionary)	{"EPSG Code": "26918", "Projection": "Transverse Mercator"}

Parsing the CSV column

When consuming the CSV in Python:

import csv, json

with open("coordinate_systems_extended.csv", encoding="utf-8") as f:
    reader = csv.DictReader(f)
    for row in reader:
        extra = json.loads(row["AdditionalInformation"])
        print(extra)  # dict of key-value pairs

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Example Records

CSV row (abbreviated)

CS_Category,Human_Readable_Name,Description,Authority,EPSG_Code,Units,DatumId,AdditionalInformation
ProjectedCoordinateSystem,NAD83 / UTM zone 18N,UTM zone 18N based on NAD83,EPSG:26918 OGP,EPSG:26918,METER,NAD83,"{""EPSG Code"": ""26918""}"

JSON record

{
  "CS_Category": "ProjectedCoordinateSystem",
  "Human_Readable_Name": "NAD83 / UTM zone 18N",
  "Description": "UTM zone 18N based on NAD83",
  "Authority": "EPSG:26918 OGP",
  "EPSG_Code": "EPSG:26918",
  "Units": "METER",
  "DatumId": "NAD83",
  "AdditionalInformation": {
    "EPSG Code": "26918"
  }
}

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FAQ

Q: Why is AdditionalInformation a JSON string in CSV but a dict in JSON? A: CSV is a flat format with no native support for nested structures. The tool serializes the dictionary to a JSON string so the CSV remains a single flat table. The JSON output keeps the native nested form.

Q: Are field names stable across runs? A: Yes. The eight field names listed above are hard-coded in the script and will not change between runs. The keys inside AdditionalInformation depend on what the source XML contains and may vary across coordinate systems.

Q: What happens if an XML element is missing? A: The corresponding field is set to an empty string ("" in CSV, "" in JSON). For AdditionalInformation, a missing or empty section produces an empty object ({} in JSON, "{}" in CSV).