# init(x:y:z:) Creates a horizontal or vertical rule mark for a 3D chart. ``` nonisolated init(x: PlottableValue, y: PlottableValue, z: PlottableValue) ``` ## Parameters `x` The x value. `y` The y value. `z` The z value. ## Discussion> Important: A 3D RuleMark requires exactly two numeric points and one numeric range. Use this initializer to create rules at positions along two axes, and a range along a third axis: ```swift Chart3D { // A red rule from from -0.5 to 0.5 on the x-axis, positioned at y = 0, z = 0 RuleMark( x: .value("x", -0.5..<0.5), y: .value("y", 0), z: .value("z", 0) ) .foregroundStyle(.red) // A green rule from -0.5 to 0.5 on the y-axis, positioned at x = 0, z = 0 RuleMark( x: .value("x", 0), y: .value("y", -0.5..<0.5), z: .value("z", 0) ) .foregroundStyle(.green) // A blue rule from from -0.5 to 0.5 on the z-axis, positioned at x = 0, y = 0 RuleMark( x: .value("x", 0), y: .value("y", 0), z: .value("z", -0.5..<0.5) ) .foregroundStyle(.blue) } ``` --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)