# IDN-3 — Copy on a product's surface carries that product's calibrated tone register — same voice character, calibrated weight, never a switched voice system

L2 · judgment · Identity

**Fails when:** copy adopts another product's register (a switched voice system, not calibrated weight) · a surface hosted inside another product carries its own nuance instead of the host's voice

## Requirement

Every product in the portfolio speaks with **one shared voice character** — the DX
voice: plain, second person, active, kind. Products differ only in **weight**, not in
system. Copy on a product's surface carries that product's calibrated register; it must
not adopt another product's register (celebratory warmth on a sensitive casework screen,
or casework reserve on an encouraging moment). This is the verbal twin of COL-1's
per-product colour rule.

## Per-product tone register

Each product declares its tone register in its own `DESIGN.md`: the register and how it
calibrates the shared voice. For example:

| Surface | Register | Calibration |
|---|---|---|
| A daily-use workspace | Calm daily command centre | Neutral, steady, quietly confident |
| A sensitive casework product | Higher gravity | More reserved, restrained celebration, privacy-forward |
| An encouragement product | Lighter, encouraging | Warmer accents, more celebratory moments |

A product may declare surfaces it hosts that carry its register with no nuance of their
own.

## Rationale

Voice is identity. People recognise a product partly by how it talks to them; a page
that switches register reads as if a different team wrote it, and on a sensitive
casework screen a bubbly register is not just off-brand but tonally wrong. The shared
character keeps the portfolio coherent; the calibrated weight keeps each product itself.
This is not CNT-2/CNT-3 (plain-language naming, lead-with-purpose) — those are the voice
*mechanics*, the same everywhere; this is the per-product *weighting* of that one voice.

## How to verify

**Judgment.** The evaluator reads the surface's copy against the register the product
declares in its `DESIGN.md`. Does it hold the shared character at that product's weight,
or has it switched systems? The failure is a *switched register*, not a shared voice —
flag encouragement-style celebration on a sensitive casework surface, casework-style
reserve on an encouraging moment, or product nuance on a hosted surface the host declares
as carrying its own voice.

## Evaluator guidance

**Flag:** copy that adopts another product's register (a switched voice system); a
declared hosted surface carrying its own nuance instead of the host's voice.

**Do not flag:** a product using the shared voice character (that is correct, not a
finding); calibrated weight within the shared system; a deliberate, reasoned deviation
carrying an inline `dx-waive IDN-3 reason="…"` (L2).

**Deconfliction.** COL-1 is the per-product *colour* register; this is the per-product
*tone* register — orthogonal (a surface can pass one and fail the other). CNT-2/CNT-3 are
portfolio-wide voice mechanics this control depends on, not restates. IDN-4 hardens the
sensitivity of casework surfaces into a concrete prohibition on gamified/celebratory
*elements* (not just copy) — this control covers the words, IDN-4 covers the interface
treatment.