# Gs1 element string parse

`gs1-element-string-parse` · version 1.0.0 · Identifiers & check digits · free, no key needed

Parse a bracketed or FNC1-separated GS1 element string into typed AI fields: implied decimals, dates and check digits.

**Use when you need to: parse a gs1 element string · decode gs1-128 application identifiers · split a gtin barcode payload into ai fields.**

## Decide before calling

Read the [versioned contract](/v1/tools/gs1-element-string-parse/versions/1.0.0) and the supported scope below. Reuse `gs1-element-string-parse@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `gs1-element-string-parse@1.0.0` for parse a gs1 element string. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- parse a gs1 element string
- decode gs1-128 application identifiers
- split a gtin barcode payload into ai fields
- parse implied decimal net weight ai 310
- decode a gs1 batch lot and expiry date barcode
- read fnc1 separated application identifiers

## Not supported

- the full GS1 Barcode Syntax Dictionary AI table (only 00, 01, 10, 11, 17, 21, 3100-3105, 37 are supported; any other well-formed AI throws unsupported_input)
- validating a single bare key without AI brackets (use gs1-key-validate)
- decoding a raw GS1 DataMatrix/QR binary payload (text must already be decoded to characters, including a literal GS U+001D for raw mode)

## Behavior

- This tool supports a fixed 8-AI subset (data_version 'gs1-ai-subset-8-2026-10-01.1ea02f4e3b81'): 00 SSCC (fixed 18 digits, check_digit_valid set), 01 GTIN (fixed 14 digits, check_digit_valid set), 10 BATCH/LOT (variable 1-20 ASCII letters/digits), 11 PROD DATE (fixed 6-digit YYMMDD, date set), 17 USE BY OR EXPIRY (fixed 6-digit YYMMDD, date set), 21 SERIAL (variable 1-20 ASCII letters/digits), 3100-3105 NET WEIGHT (kg) (fixed 6 digits, decimal set), 37 COUNT OF ITEMS (variable 1-8 digits). Any other well-formed 2- or 4-digit AI throws unsupported_input; a malformed AI code throws invalid_input. value is always the exact captured field text, never reformatted.
- Implied-decimal rule (3100-3105 only): n is the AI's 4th character (0-5); decimal is value with '.' inserted so exactly n digits follow it (n=0: decimal equals value, no dot).
- Date rule (11 and 17 only): YY maps to 2000+YY when YY<=50, else 1900+YY; MM must be 01-12; DD='00' means the last day of that Gregorian month/year (leap years divisible by 4 except centuries not divisible by 400), otherwise DD must be a valid day of that month, else the whole request throws invalid_input. date is 'YYYY-MM-DD'.
- check_digit_valid (00 and 01 only) is the GS1 mod-10 check over value, its own last digit as the check digit.
- mode 'bracketed': text is one or more '(' + AI + ')' + VALUE groups, VALUE running to the next literal '(' or end of text; a GS anywhere throws invalid_input; a parenthesized code not in the supported subset throws unsupported_input if it is itself 2 or 4 digits, else invalid_input.
- mode 'raw': repeatedly read 2 digits as the AI (4 if they are '31' followed by a digit 0-5 forming 3100-3105); a fixed-length AI consumes exactly its declared length next; a variable-length AI reads to the next GS (U+001D) or end of text, consuming that GS as a separator (an immediately-following GS, empty value, or a GS anywhere else -- e.g. right after a fixed-length value, or two GS in a row -- throws invalid_input).
- Elements are returned in text order; more than 10 elements throws limit_exceeded. Pure string parsing, a pinned fixed AI table and integer/calendar arithmetic; no locale, clock, Intl, or randomness.

## Input

- `text` (string, required): min length 1; max length 200
- `mode` (one of "bracketed", "raw", required)

## Output

- `elements` (array of object, required): max items 10
- `data_version` (constant "gs1-ai-subset-8-2026-10-01.1ea02f4e3b81", required)

## Limits

- max text bytes: 200
- max elements: 10

## Example

Request input:

```json
{
  "text": "(01)04006381333931",
  "mode": "bracketed"
}
```

Response:

```json
{
  "result": {
    "elements": [
      {
        "ai": "01",
        "title": "GTIN",
        "value": "04006381333931",
        "decimal": null,
        "date": null,
        "check_digit_valid": true
      }
    ],
    "data_version": "gs1-ai-subset-8-2026-10-01.1ea02f4e3b81"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "gs1-element-string-parse",
  "version": "1.0.0",
  "input": {
    "text": "(01)04006381333931",
    "mode": "bracketed"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/gs1-element-string-parse/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"text":"(01)04006381333931","mode":"bracketed"}'
```

The machine-readable contract is at [/v1/tools/gs1-element-string-parse/versions/1.0.0](/v1/tools/gs1-element-string-parse/versions/1.0.0).

### CLI

```sh
node cli.mjs run gs1-element-string-parse 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Upu s10 validate](/tools/upu-s10-validate): Validate a 13-char UPU S10 postal identifier's weighted mod-11 check digit, split service indicator and country.
- [Checkdigit compute](/tools/checkdigit-compute): Compute the check digit(s) for a payload under a named algorithm (Luhn, Verhoeff, Damm, ISO 7064, GS1, mod 10).
- [Doi parse](/tools/doi-parse): Parse a DOI (bare, doi: or doi.org URL) into prefix, suffix, directory indicator, registrant code and canonical forms.
- [Gs1 key validate](/tools/gs1-key-validate): Validate a GTIN-8/12/13/14, GLN, SSCC or GSIN's GS1 mod-10 check digit and look up its 3-digit GS1 prefix meaning.
- [Iccid validate](/tools/iccid-validate): Validate a 19/20-digit ICCID's Luhn check digit, require the 89 major industry id, split issuer/account digits.
- [Imei validate](/tools/imei-validate): Validate a 15-digit IMEI's Luhn check digit or accept a 16-digit IMEISV, and split the TAC from the serial.