UAX #14 rev. 57, Section 5: LB21a is listed among rules that use East_Asian_Width, General_Category and Extended_Pictographic

Section 5 lists the rules that use tailorable East_Asian_Width, General_Category and Extended_Pictographic values: LB15a, LB15b, LB19, LB19a, LB21a, LB30 and LB30b. LB21a, “HL (HY | HH) × [^HL]”, uses only line break classes.

Consequence

A reader who tailors these properties looks for an effect on LB21a that does not exist; no break changes.

Proposed correction

Remove LB21a from the list.

Issued by

Unicode Consortium — Unicode Technical Committee

Act

UAX #14 revision 57 (Unicode 18.0.0)

Place

Section 5, introduction

Record

Discrepancy

Class

Text of the act

Where it arose

The text of the act

Arxo's conclusion

Confirmed

Official text

Unchanged at last check

Last checked

2026-10-31

Evidence

Contradiction within the text. Quotations are verbatim from the official material; translations are ours and marked.

In addition to the line breaking properties defined in this section, the algorithm defined in Section 6, Line Breaking Algorithm also makes use of East_Asian_Width property values, defined in Unicode Standard Annex #11, East Asian Width [ UAX11 ], as well as the General_Category and Extended_Pictographic properties. Note that for purposes of the line breaking algorithm, those property values are tailorable, as are the rules of the line breaking algorithm which use them. (See rules LB15a, LB15b, LB19, LB19a, LB21a, LB30, and LB30b .)

How to check it without Arxo's tools

1. Open UAX #14 revision 57 (Unicode 18.0.0), Unicode Consortium and find Section 5, introduction. Compare the text with the quotation above. A copy is kept in this register: 296df5332aefe695-tr14-57.html (SHA-256 296df5332aefe695b4951b511288b118bc6a7b43db7fadfd60f6062096acc7c0, copy of the official file).
2. The finding holds if the quoted passages read as shown and the comparison gives the result stated at the top of this page. If it does not, write to us with the record ID.

How this finding was made

AI agents read the annexes and the data files and compared them; the examples were run through published implementations. An AI coordinator checked each place against the full annex and the trackers, and two further AI models checked the report before filing.

Responsible institutions

• Unicode Consortium — publishes the annex and the Unicode Character Database

Reported to

Responses

No response recorded.

History

1. 2026-10-31Confirmed by Arxo
2. 2026-10-31Entered in the register
3. 2026-10-31Reported to Unicode Consortium (e-mail)

Cite this record

Arxo Law, Arxo Findings Register, ARXO-2026-0462, https://arxo.io/findings/ARXO-2026-0462/ (status as of 2026-10-31). Data: ARXO-2026-0462.json.