%BB

# Explanation of the Metatrader MQL Script Logic

The script provided is a technical analysis indicator called "Percentage Bollinger Bands" (%BB), which operates within the MetaTrader platform. It aims to give users an insight into market conditions by displaying how current prices relate to a range defined by Bollinger Bands.

## Key Components of the Indicator:

1. **Bollinger Bands**: These are bands that consist of a middle line (usually a simple moving average) and two outer lines. The width between these lines changes based on market volatility. In this script, parameters like `Bands_period` and `Bands_deviation` determine how these bands are calculated.

2. **Indicator Settings**:
   - **Separate Window**: This setting means the indicator will be displayed in its own window rather than overlaid on a chart.
   - **Buffer**: The indicator uses one buffer to store computed values, which is necessary for displaying data over time.
   - **Colors and Levels**: These settings determine how the lines are drawn (in red) and establish three horizontal levels at 0%, 50%, and 100% for reference.

3. **Customization Parameters**:
   - `Bands_period` (default: 20): This is the period of the moving average used to calculate the middle band.
   - `Bands_deviation` (default: 2): This defines how many standard deviations away from the moving average the upper and lower bands are drawn.

## How the Script Works:

### Initialization:
- The script begins by setting up its visual style and buffer. It configures the line style for drawing, sets which buffer will hold the data (`PercentBB`), assigns a label (%BB), and determines where to start drawing from on the chart (based on `Bands_period`).

### Deinitialization:
- This function is called when the indicator is removed or reset. Currently, it does not perform any actions.

### Iteration Process:
- The main logic of the script occurs in this phase. It calculates how far the current closing price is within the Bollinger Bands range as a percentage.
- **Steps**:
  - Determine how many bars have already been processed (`counted_bars`).
  - Iterate over each bar that hasn't been counted yet, starting from the earliest to the most recent.
  - For each bar, calculate the lower band (`LB`) and upper band (`UB`) using the `iBands` function with specified parameters like period and deviation.
  - Compute the percentage position of the current closing price within the Bollinger Bands using the formula:
    \[
    \text{PercentBB} = \left(\frac{\text{iClose} - LB}{UB - LB}\right) \times 100
    \]
  - This value is stored in the `PercentBB` buffer for each bar, representing how close the price is to the lower band (0%) or upper band (100%).

## Purpose:

The %BB indicator provides a straightforward way to assess whether the current market price is near the extremes of its recent volatility range. A percentage closer to 0% indicates that prices are near the lower band, suggesting potential bullish momentum, while a value near 100% suggests bearish conditions as prices approach the upper band.

This intuitive visualization helps traders make more informed decisions by offering a clear depiction of price behavior relative to historical volatility.