Legend text must stay in sync with the actual function; changing the function without changing the legend misleads

What it is

The cap still says “MENU”; firmware has turned the key into a voice assistant. The knob is still numbered 1–10; the software range is already 0–100. A stale legend makes the reading channel lie. Wear is letters gone; desync is letters still there, pointing at a function that has moved. People will expect what the letters say, which is worse than no letters.

Why it happens

Physical legends revise on a tooling and print-batch clock; software functions revise on a release clock. Once those clocks split, the fields drift. Users retrieve by legend: look for “menu,” press MENU, get an assistant—menu not found, assistant false-triggered. Fluent users switch to muscle memory and stop reading; the error is dumped onto newcomers and occasional users. Support tickets of this kind are often filed as “can’t find the function”; the root is that the map and the territory are no longer one sheet. Stickers, post-laser, e-ink caps chase software with a faster legend clock; if you will not chase, do not change that key’s meaning.

Studying it

Diff cap photos against the function list before and after a release, then have people who have not read the notes find functions by legend.

Independent variables: whether the legend changed with the function, word versus icon change, presence of release notes, whether people used the previous generation. Dependent measures: whether following the legend yields the current function, time to find a new function using an old legend, false triggers.

Release notes are not “already in sync” in the comparison. The field must assume notes were not read. Report previous-generation users and true newcomers separately: the former may ignore legends, the latter will trust them.

Where it stops holding

An unmarked encoder never had a function word; desync moves to a neighboring display—and that display’s name must still match current meaning. Legally frozen legends (some medical and aviation terms) cannot be renamed for marketing; freeze the function, do not freeze the legend and change the function. Locale-specific print (the same key carrying different words in different countries) is not desync if each set matches local firmware. A wear-blank at least tells people they are guessing; a crisp, outdated false word is more dangerous.

Applying it

• Changing a shipped key’s function is a change that must retouch the cap, the print, or a persistent neighbor name. If the legend cannot change, do not change the meaning.
• Release notes are not a substitute for sync.
• Verify: show people who have not read the notes a cap photo and ask what pressing it yields, against current firmware. Every wrong answer is an unsynced key. Test previous-generation users separately on whether they still hunt functions by the old word.

Related

• Same group: C10.14.1 Engraved or printed legends can become unreadable as they wear · C10.14.2 Backlit legends solve dark readability but add power draw and structural complexity · C10.14.4 Icon legends need cross-cultural checks; do not lean on one region’s graphic conventions
• Adjacent: C10.13 Mode Problems in Multifunction Physical Controls · C10.07 Tradeoffs Between Physical and On-Screen Controls
• Search: stale legend · mislabeled control · label-function sync