The Marker Line tool in the Detail tab is used to add elevation level lines and plan titles to your drawings. It helps indicate important reference levels, such as finished floor level, ceiling height, or other key elevations. This tool is especially useful for sections and elevation views where height information needs to be clearly shown.

To use the Marker Line tool, select the Detail tab and click the marker line icon. Then click and drag in the drawing area to place the line at the desired location. While drawing, hold the SHIFT key to release the angle constraint or hold the CTRL key to lock the segment angle. After placing the line, you can modify its style, text, and attributes in the Properties panel.

Marker lines improve the clarity and professionalism of your construction documents. They make it easier to communicate elevation information and ensure accurate interpretation of building heights and reference levels.