When using variable height, vertical offset can be specified as a positive or negative distance from top of wall.

The image below demonstrates this.

• A: Top of Wall
• B: Bottom of Wall
• 1: Vertical Offset 0’-0”; Height 0’-0”
• 2: Vertical Offset -1’-0”; Height -1’-0”
• 3: Vertical Offset -1’-0”; Height 1’-0”