# Preliminary_Action A specific task that a trigger performs. ## Discussion Because it inherits `Typed`, this schema declares a `Preliminary_Action` as a type of prim. For more information about typed schemas, see USD Specification > [Typed](http://graphics.pixar.com/usd/docs/USD-Glossary.html#USDGlossary-TypedSchema). When a behavior executes an action, the behavior modifies the state of the scene dynamically. For example, an action might start an animation, change the location of a prim, or start playing audio. ### Declaration ```swift class "Preliminary_Action" ( inherits = ) ``` ### Define an action that slides a cube The following example shows an action prim called `PushCube` that affects an impulse feature. ```swift #usda 1.0 def Cube "Cube" {} def Preliminary_Action "PushCube" { uniform token info:id = "Impulse" rel affectedObjects = [ ] uniform vector3d velocity = (1.0, 0.0, 0.0) } ``` ## Topics ### Properties [info:id](/documentation/USD/info-id) The action’s unique identifier. [multiplePerformOperation](/documentation/USD/multipleperformoperation) An option that indicates how an action handles an additional invocation while running. --- 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)