The advance-decline line is breadth in its purest form: a running sum of how many stocks rose versus fell each day. When it diverges from the index — the Nifty climbing while the A-D line sags — participation is narrowing beneath the surface.
Trendvue computes daily advancers, decliners and the cumulative A-D line across the whole market after every close, so you can confirm a trend or catch a divergence before it shows up in the headline index.