@s57-parser/iso8211

Pure TypeScript parser for the ISO/IEC 8211 binary format, the container used by IHO S-57 and S-100/S-101 electronic navigational charts.

Zero dependencies. ESM only. Works in Node.js 18+, Bun, Deno and browsers.

npm install @s57-parser/iso8211

Usage

import { readFileSync } from 'node:fs';
import { parse } from '@s57-parser/iso8211';

const b = readFileSync('US5MA12M.000');
// Copy into a standalone ArrayBuffer: Node buffers can be views into a shared pool.
const buffer = b.buffer.slice(b.byteOffset, b.byteOffset + b.byteLength);

const file = parse(buffer);
console.log(file.ddr.directory.map(d => d.tag)); // ['0000', '0001', 'DSID', ...]

const dsid = file.records[0].fields.find(f => f.tag === 'DSID')!;
for (const sf of dsid.subfields) console.log(sf.label, sf.value);
// RCNM 10, RCID 1, ..., DSNM 'US5MA12M.000', ...

parse() reads the Data Descriptive Record (DDR), then decodes every data record's fields into typed subfields using the DDR format controls:

| Format | Decoded as | |--------|------------| | A, A(n) | { type: 'string' } (variable length up to a unit terminator, or fixed width) | | I, I(n) | { type: 'int' } | | R, R(n) | { type: 'real' } | | b1n | { type: 'uint' }, n bytes little-endian | | b2n | { type: 'int' }, n bytes little-endian two's complement | | B(n) | { type: 'uint' }, n bits |

Repeating groups (labels starting with *, e.g. *YCOO!XCOO) are decoded by cycling through the format controls; labels keep the * prefix. Each field also keeps its raw bytes.

parse() throws an Error when the buffer is not ISO 8211 (truncated leader, inconsistent record length or base address).

API

• parse(buffer: ArrayBuffer): ISO8211File
• Types: ISO8211File, ISO8211Record, ISO8211Leader, ISO8211DirectoryEntry, ISO8211Field, DataDescriptiveField, FormatControl

Part of s57-parser. MIT licence.