This is an optional indicator for "NK-Box". It can draw lines in the exact same range as "NK-Box".
While NK-Box uses the midline as a reference, this indicator allows you to set background colors between other calculated lines.
Additionally, it can highlight the gap from the previous period in the background.

Chart display example of option1_Zone & Gap
Source: TradingView

⇩ "Hist" (Top), "Current" (Bottom)