Bar Lines feature lets you write a formula and draw a horizontal line anywhere on the chart at the current formula value. To add a Bar Line, select Studies --> Custom Study Wizard.

Click New to create a new bar line or select one of the existing bar lines and click Edit to edit it.

Specify the name of the bar line and use Formula Wizard to create the formula. The following example demonstrates how to create a bar line at yesterday's (high+low+close)/3:

The new bar line will appear in the list of custom studies allowing you to overlay it on any study. Right-click on the price chart and select the new bar line study from the Overlay menu:

Custom Study properties dialog will popup:

• Configure color and thickness
• Display mode: select "Horizontal @ last bar's value".
• Vertical Scaling mode: select Normal. "Exclude from vertical scaling" mode is useful when the bar line is far away from the price range and you don't need to see it until price and line converge.
• Whether to display Y-axis label for the bar line (useful when Y-axis becomes cluttered with many studies)
• Whether to override all intervals within the bar line formula with the current chart interval. If you want to combine multiple intervals (timeframes) on the same chart, uncheck this setting.
• Alternate Symbol is specified to override the current chart symbol when calculating the bar lines formula (useful for symbol overlays).

Click here for Pivot Lines Examples