An X-Particles emitter will always create certain basic data for all particles, such as speed, direction, color, etc.
But in some cases additional data may be required for certain functions.
Always including this data, even when it will never be required, may slow down the particle engine, so this extra data is only stored when required.
In some cases the extra data will be added automatically, but in others you must specify that you require this data.
For example, if you want to use particle rotations, you must enable Use Rotation in the rotation data section of this tab.
Extended Data tab menu.
This group of settings determines particle rotation and spin.
If you want to rotate or spin your objects, you must turn on particle orientation in the emitter.
By default, rotation is not enabled since it requires significant extra data to be allocated to the particle.
If you don't need to rotate the particles or generated objects, leave Use Rotation unchecked.
If an xpSpin modifier is affecting the particles, the modifier will override the Set and Random modes for rotation and will also override the Simple Spin settings.
This is to prevent conflicts between the emitter and the modifier when rotating particles.