Most actions in Particle Flow operate on particles in either of two time frames: once, when the particle first enters the event, or on a continuous basis, potentially changing particle behavior at each integration step (that is, the whole time the particle is in the action’s event). Some actions can work only in one time frame, while others can work on an instantaneous or continuous basis, depending on their settings. The tables in this topic list each action with its time frame.
| Operator | Time Frame |
|---|---|
| Birth | Once |
| Birth Paint | Once, except continuous when Lock At Painted Objects  Position or Rotation is on
|
| Birth Script | n/a |
| Birth Texture | Once, except continuous when Lock To Emitters is on |
| Delete | n/a |
| Force | Continuous |
| Group | Once |
| Group Selection | Depends on Selection Update setting |
| Initial State | Once, except continuous when Lock To Icon TM Position or Speed is on
|
| Keep Apart | Continuous |
| Mapping | Continuous |
| Mapping Object | Depends on Type setting |
| Material Dynamic | Continuous |
| Material Frequency | Once |
| Material Static | Once |
| Placement Paint | Depends on Data Update setting |
| Position Icon | Once, except continuous with Lock On Emitter |
| Position Object | Once, except continuous with Lock On Emitter |
| Preset Flow | n/a |
| Rotation | Once, except continuous with Speed Space Follow |
| Scale | Once, except continuous with Absolute and Relative options |
| Script Operator | Depends on script |
| Shape | Once, except continuous when Scale % or Variation % parameters are animated |
| Shape Facing | Continuous |
| Shape Instance | Once, except continuous with Animated Shape |
| Shape Mark | Once, except continuous with Align To Surface Animation |
| Speed | Once |
| Speed By Icon | Continuous |
| Speed By Surface | Depends on setting |
| Spin | Once, except continuous with Speed Space Follow |
| Split Group | Continuous |
| n/a=not applicable |
Most tests in Particle Flow function only as tests. At each integration step, they check each particle for the specified conditions, and then return the test result: True or False. So, as tests, they work on a continuous basis. For example, Age Test checks each particle's age at every integration step, because particles might not reach the specified age until remaining in the event for a while, and also because another action in the event might change or reset particle age.
The principal exceptions to this are the Split tests, which test each particle only when it first enters the event. That is, a Split test splits the particle stream only once for each particle that enters the event. Any particles that remain in the event are not subject again to being split off from the stream by the same test. Also, the Send Out test performs no test, but simply moves particles along to the next event.
Some tests also function as operators, in that they directly affect particle behavior. These are the ones listed here, and the specified time frame is related to the operator functionality, not the test.
| Test | Time Frame |
|---|---|
| Collision Spawn | Continuous |
| Find Target | Continuous |
| Go To Rotation | Continuous |
| Script Test | Depends on script |
| Spawn | Continuous, except once with Once |
