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Structure & Formats

A CNPJ always has 14 meaningful characters, split into three segments:

PositionsLengthSegmentMeaning
1–88Root (raiz)Identifies the entity itself; shared by the head office and every branch
9–124Branch/order (ordem)"0001" conventionally denotes the head office (matriz)
13–142Verification digitsComputed from the first 12 characters via the Módulo 11 algorithm

Cnpj exposes each segment as a borrowed accessor:

  • Cnpj::root() — the 8-character root.
  • Cnpj::branch_code() — the 4-character branch/order segment.
  • Cnpj::is_root() — true when the branch/order segment is "0001".
  • Cnpj::branch_number() — the branch/order segment as a u16, when it’s purely numeric.
  • Cnpj::check_digits() — the two verification digits, as (u8, u8).

The conventional punctuated rendering is AA.AAA.AAA/AAAA-DD; the compact rendering drops all punctuation. Both refer to the same 14 characters — see Formatting & Display.

Numeric vs. alphanumeric CNPJs

The public CNPJ format changed in 2026. Historically, all 14 characters were digits. As of the 2026 change, the first 12 positions (root + branch/order) may also contain uppercase letters; the final two verification digits remain numeric either way.

This crate follows Nota Técnica Conjunta COCAD/SUARA/RFB nº 49/2024, which defines the checksum so that the legacy numeric-only calculation is unchanged — it’s simply the special case where every character happens to be a digit. Each character contributes its ASCII code minus '0' to the Módulo 11 sum:

  • Digits contribute their own value ('0' → 0, …, '9' → 9).
  • Uppercase letters contribute 17 through 42 ('A' → 17, …, 'Z' → 42).

Because of this, there is no separate “legacy” type in this crate. Cnpj represents both numeric-only and alphanumeric CNPJs uniformly, and there’s a single code path (and a single test suite) validating both.

use ftracker_identifiers::Cnpj;

// A numeric-only CNPJ (the historical format).
let numeric = Cnpj::parse("00.000.000/0001-91").unwrap();

// An alphanumeric CNPJ (the 2026 format) — same type, same validation.
let alphanumeric = Cnpj::parse("12ABC34501DE35").unwrap();
assert_eq!(alphanumeric.branch_code(), "01DE");

A note on ordering

Cnpj derives Ord directly over its underlying ASCII bytes, which matches str ordering on Cnpj::as_str(). Because ASCII digits ('0'..='9') sort before uppercase letters ('A'..='Z'), a numeric-format CNPJ always sorts before any alphanumeric CNPJ sharing the same leading digits. This is lexicographic string order, not a numeric or chronological order — don’t read a sorted list of Cnpj values as meaning “issued earlier” or “smaller root number.”