---
title: "Is WXF Notation Case-Sensitive for Red and Black? · Xiangqi Master"
description: "In many computer formats, yes, uppercase letters typically represent Red's pieces and lowercase letters represent Black's, though human-readable WXF move notation itself usually relies on context instead."
url: https://xiangqimaster.com/blog/is-wxf-notation-case-sensitive-for-red-and-black
updated: 2026-09-23
source: Xiangqi Master (https://xiangqimaster.com)
license: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/)
---

# Is WXF-style Roman-letter notation case-sensitive, with uppercase and lowercase distinguishing Red from Black?

These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.

> Direct answer
>
> **In machine-readable formats, generally yes.** Formats built for software, including the widely used xiangqi FEN-style board notation, commonly use uppercase letters for Red's pieces and lowercase for Black's, so the same letter can mean either side depending purely on its case. The move notation a human reads over the board, by contrast, usually relies on context, whose turn it is, rather than on case to tell the sides apart.

## Why software formats need the distinction explicit

A program parsing a position from scratch has no inherent sense of "whose turn it naturally is" the way a human following a game does; it needs every piece's owner stated unambiguously in the data itself. Case is a simple, compact way to do that without adding extra characters.

## Why human notation gets away without it

A reader following a game already knows whose move comes next simply by counting, so the same letter appearing in Red's line and Black's line is never actually ambiguous in context. Adding case sensitivity on top would be redundant information for a human reader, even though it is essential for a program starting from nothing.

## Related questions

Does this affect the WXF letters like C for chariot or N for horse?

The letters themselves stay the same for both sides; only their case changes in formats that use case to mark ownership.

Is this the same convention chess's FEN uses?

Yes, the same uppercase-for-one-side, lowercase-for-the-other convention chess popularised is what xiangqi's own FEN-style notation follows.

## Related xiangqi resources

Reading notation

炮二平五 and C2=5 — the same move, two ways

Board setup

The board, the river, the palace, and where the 32 pieces go

Xiangqi rules

The complete reference, rule by rule

## Try it on a real board

Reading an answer is one thing; playing it is another. Free, instant, and nothing to install.