Code 2 of 5 Data Logic (China Post) — format provenance and usability
=======================================================================

This file records the engineering provenance and redistribution boundary for
the Data Logic 2 of 5 format implemented by Sythos Barcode Universal.

It is an engineering inventory, not legal advice. Patent, copyright and
trademark conclusions still need independent review for the jurisdiction and
the intended product. Items marked [TO VERIFY] remain open questions.


FORMAT AND IMPLEMENTATION BASIS
-------------------------------

Data Logic 2 of 5 (also documented as China Post Barcode, "2/5 Data Logic")
is a numeric-only symbology from the same 1968-1972 "2 of 5" family as the
Code 25/Industrial/IATA profiles already in this SDK, sharing their era and
public-technical-description basis. It reuses the short IATA-style start/stop
frame with a distinct digit grammar in which both bars and spaces carry
width information.

The run-width descriptions are represented as original Sythos data and
expanded algorithmically for the selected wide-bar ratio. The reader
validates the full start/data/stop structure, quiet-zone boundary and
optional check digit before returning a value; the 2:1 wide:narrow ratio is
intentionally rejected by both the writer and reader because it produces a
reversed-image ambiguity in this specific digit grammar (verified by
exhaustive round-trip testing across payloads, scales and ratios during
implementation). No third-party source code, lookup table or binary asset is
copied into this repository.

The runtime is original Sythos TypeScript with generated JavaScript output
and is distributed under the MIT License. The format name is descriptive and
does not imply certification by China Post, Datalogic S.p.A. or any other
organisation.


PATENT AND TRADEMARK REVIEW
---------------------------

As with the rest of the Code 25 family, historical patent families,
jurisdiction-specific licensing statements and current registrations for the
"Data Logic" and "China Post Barcode" names have not been independently
cleared here. [TO VERIFY] This project makes no unconditional patent-free,
public-domain or trademark-clearance claim. The format's association with a
national postal operator (China Post) and a named vendor (Datalogic) is
noted but not itself treated as a usability blocker, consistent with how
this project treats other operator-named postal and logistics formats
already implemented (see `postal.license`).


INDEPENDENT VALIDATION BOUNDARY
--------------------------------

Zint (libzint, BSD-3-Clause) was used only as a local, independent black-box
oracle to cross-check the digit width table against a published open-source
implementation before this SDK's own original data structures were written.
Its source, tables and runtime are not copied into or shipped by this SDK,
and it is not a runtime dependency. The comparison is an engineering check,
not a legal opinion or a conformance certificate.


CONCLUSION
----------

The original Sythos Data Logic 2 of 5 implementation is MIT-licensed. If a
rights holder or user identifies a conflicting notice about the available
material, please open a GitHub issue with the reference so it can be
reviewed and recorded.