English authoring rules for Korean-origin device documentation
Internal standard for engineering and clinical staff drafting English source text that will go into an MDR technical file and a patient-facing IFU.
1. Why this standard exists
English source text is translated into every other market language. An ambiguity in the English is reproduced in each target language and is usually found late, at readability testing or during notified-body review. Correcting it then means re-testing the IFU and re-issuing every translation. The rules below address the patterns that most often cause that rework.
2. One instruction per sentence
A procedural step contains one action. Where the source sentence joins two actions with a conjunction, split it.
| Instead of | Write | Why |
|---|---|---|
| "After cleaning the skin and confirming it is dry, attach the band and press the power button." | "1. Clean the skin and dry it completely. 2. Attach the band. 3. Press the power button." | Four actions in one sentence. A user who is mid-task cannot find their place, and a tester cannot verify which step failed. |
| "The device should be charged regularly." | "Charge the device after every third session." | "Should" and "regularly" are both unverifiable. State the interval. |
3. Articles and number
Korean does not mark articles or plural number the way English does, so these are the two most frequent corrections at review. Two rules cover most cases:
- Use the for a part the device has exactly one of: the power button, the charging port, the strap.
- Use a on first mention of something the user supplies: "Use a lint-free cloth." Then "the cloth" thereafter.
4. Modal verbs carry regulatory weight
These words are not stylistic choices. Use them as defined and do not substitute synonyms.
| Word | Use for | Never use for |
|---|---|---|
shall | A requirement in a specification or protocol | Patient-facing text — use the imperative instead |
must | An obligation on the user where non-compliance causes harm | A recommendation |
do not | A prohibition | Softening to "avoid" or "it is not recommended" |
may | Permission, or a possible outcome | An obligation |
5. Warnings state hazard and consequence
A warning that states only the prohibition fails review. Give the user the reason, because the reason is what makes them comply.
6. Terminology is fixed, not varied
English style rewards variation. Regulated documentation does not. One concept has one term across the IFU, the labelling, the app interface and the technical file. The approved term list is maintained in the termbase and enforced at translation.
| Approved | Do not use |
|---|---|
| band | device, wearable, strap unit, sleeve |
| session | workout, training, exercise period, programme run |
| healthcare professional | doctor, therapist, clinician, physician |
| electrode | sensor pad, contact, lead |
Where the app interface and the IFU disagree, the app is changed to match the IFU, not the reverse. The IFU is the controlled document.