This indicator is designed to be used with Market Profile / Volume Profile trading techniques on a 30min chart.
The halfback of a candle is the mid point between the high and the low of the candle. A halfback trade can be taken once price retraces into this point as support/resistance using the prevailing trend as your trade direction.
One-Time-Framing is a...
This is a line plotted at the 505 retrace of a swing high swing low move, it has an adjustable look back period, with a default setting on 60 bars.
The purpose for me is when we have a decent move in one direction any retracement that does not get past the 50% area of the move is a decent trade in the direction of the first move.