ISO 24495 Skill — Plain Language for English and Traditional Chinese

A Claude Code skill that rewrites text into plain language per ISO 24495-1:2023 — the international standard that defines plain language by reader outcome: the intended readers can find what they need, understand it on first reading, and use it.

Two things make this skill different from a one-line "write plainly" prompt:

1. It implements the standard's actual structure — reader-first content selection (relevant), document structure (findable), wording (understandable), and actionability (usable) — not just shorter sentences.
2. It ships a real Traditional Chinese technique layer（繁體中文層）. ISO 24495-1 is explicitly language-independent, but as of this release the official translation list contains no East Asian language at all. The Chinese layer here is an original implementation of the four principles for Chinese — targeting the problems Chinese text actually has（歐化長句、公文腔、成語堆疊、中英夾雜、 被字句濫用）, not a translation of the English rules.

Before / After

More pairs, each naming the principle applied: examples/before-after-en.md · examples/before-after-zh.md.

What This Skill Does

1. Identifies the intended reader and purpose — the standard's first principle requires it, and every cut/keep decision follows from it.
2. Detects the text language and loads the matching technique layer: references/english-techniques.md or references/chinese-techniques.md.
3. Rewrites against the four principles (relevant → findable → understandable → usable) without dropping any fact, number, condition, or honest hedge. Where plainness would cost precision, it keeps the precision and flags the trade-off.
4. Returns the rewritten text alone — no preamble, no lecture. Ask for "show the diff" and it returns a before/after table naming the principle behind each change instead.

Architecture: one shared layer, per-language technique layers

SKILL.md                          shared layer (English): principles, procedure, routing
references/principles.md          the four principles, interpretation, sources
references/english-techniques.md  English techniques (in English)
references/chinese-techniques.md  中文手法（以中文撰寫）

The shared layer is language-independent, mirroring the standard itself. Technique layers are written in their own language, because plain language techniques do not translate: English fights nominalization and passive voice; Chinese fights Europeanized long sentences and bureaucratic register. Adding another language = adding one technique file. Contributions welcome.

Installation

git clone https://github.com/danyuchn/iso-24495-skill ~/.claude/skills/iso-24495

Usage

Rewrite this in plain language
Apply ISO 24495 to this announcement
把這段改成淺白中文
幫我去掉這封信的公文腔

You get the rewritten text back and nothing else. Add "show the diff" / 「列出改了什麼」 to see the per-change principle table.

Scope

Built for: reader-facing text — reports, emails, documentation, UI strings, announcements, policies, explanations, and AI output that reads as dense or bureaucratic. Works on English and Traditional Chinese; the principles apply to other languages but no technique layer exists for them yet.

Not built for: creative or literary writing (voice is the point there), and not for agent-facing text where a machine must parse without ambiguity — that is controlled-language territory; use the companion skill asd-ste100-skill instead. Rule of thumb: reader is a person → this skill; reader is a machine or a maintenance manual → STE.

Relationship to the ISO Standard

This is an unofficial project, not affiliated with, endorsed by, or approved by ISO. The full ISO 24495-1 text is a licensed document and is not reproduced here. The skill is built from the standard's publicly documented principle framework (ISO's published abstract and scope, and the International Plain Language Federation's freely published materials). Every quantitative rule in the technique files is this project's own working proxy, not a clause of the standard. For certified conformance, buy and consult the standard.

Sources

• ISO 24495-1:2023 — Plain language, Part 1
• International Plain Language Federation — ISO standard
• IPLF — national adoptions and translations
• AccessibleEU — ISO 24495-1 summary
• Companion controlled-language skill: asd-ste100-skill

License

MIT — see LICENSE. The license covers this repository's original text; it grants no rights to any ISO publication.