# Clips & Phases: Scheduling

> How a play actually happens.

Glider documentation · Animation · Web page: https://cgglider.com/docs/clips/scheduling/

Sections of this page: [Phases](https://cgglider.com/docs/clips.md) · [Scheduling](https://cgglider.com/docs/clips/scheduling.md) · [Clip events & chaining](https://cgglider.com/docs/clips/events.md)

- A play compiles the clip against the current scene, resolving a scene target to every node on the layer and a group target through its nested subgroups.
- If the clip compiles to no targets, the play is abandoned rather than silently doing nothing.
- If the target elements are not mounted yet, the scheduler retries up to six times at 50 ms — enough to cover a scene that has just been taken.
- Play signals carry a timestamp and are de-duplicated with a monotonic high-water mark, so a replayed frame does not fire the same clip twice.

> **One implementation, three surfaces:** The editor canvas, the Output tab and the live page all run the same scheduler. What you rehearse is what goes to air.