Delta SMA 1-Year High/Low Strategy

### Summary:
This Pine Script code implements a trading strategy based on the **Delta SMA (Simple Moving Average)** of buy and sell volumes over a 1-year lookback period. The strategy identifies potential buy and sell signals by analyzing the relationship between the Delta SMA and its historical high/low thresholds. Key features include:

1. **Delta Calculation**:
- The Delta is calculated as the difference between buy volume (when close > open) and sell volume (when close < open).
- A 14-period SMA is applied to the Delta to smooth the data.

2. **1-Year High/Low Thresholds**:
- The strategy calculates the 1-year high and low of the Delta SMA.
- Buy and sell conditions are derived from thresholds set at 70% of the 1-year low and 90% and 50% of the 1-year high, respectively.

3. **Buy Condition**:
- A buy signal is triggered when the Delta SMA crosses above 0 after being below 70% of the 1-year low.

4. **Sell Condition**:
- A sell signal is triggered when the Delta SMA drops below 60% of the 1-year high after crossing above 90% of the 1-year high.

5. **Visualization**:
- The Delta SMA and its thresholds are plotted on the chart for easy monitoring.
- Optional buy/sell signals can be plotted as labels on the chart.

This strategy is designed to capture trends in volume-based momentum over a long-term horizon, making it suitable for swing or position trading.