Day Indicator
A watch function or complication known as Day Indicator, adding information or capability beyond basic time display.
Also known as: Day display, Day-of-week indicator, Weekday display
Definition
A day indicator displays the day of the week, either in full, abbreviated in an aperture, or with a pointer on a seven-position scale. In mechanical watches it normally advances once every 24 hours from a seven-position day wheel or equivalent mechanism. Unlike the numbered date, the seven-day cycle never needs month-length correction, although it must be set correctly after the watch has stopped for long enough to lose calendar synchronisation.
Why it matters
It is simple but genuinely useful, especially when combined with date. The main ownership issue is synchronising it correctly after the watch has stopped or the calendar has been reset.