M3 (3 minutes) joins the available timeframes, between M1 and M5. It works everywhere: as a backtest base timeframe, as a condition timeframe, as a chart timeframe, and in the Pine Script export to TradingView.
M3 fills a real gap for scalping: M1 is often too noisy to give a reliable signal, M5 too slow for a precise entry. History goes back as far as it does on every other timeframe β up to 10 years.