Many plugins share common conditions, actions and expressions, such as for the object's size and position. Rather than repeating the descriptions of these for each plugin, they are listed in this section.
Not all objects use all the common features; some may use only a few of the ones listed here. This is provided as a reference for the features shown to you in Construct 2 rather than describing any particular plugin's features.
All objects at runtime have a unique ID assigned, which is a number starting at 0 for the first instance and incrementing by 1 for every other instance. It is returned by the object's UID expression. This number can be used to uniquely identify a single instance throughout an entire game. For example, it can be stored in instance variables or event variables and later picked again by using the Pick by unique ID condition.
All objects at runtime have an index ID assigned, which is the number of the instance within its own object type. It is returned by the object's IID expression. For example, the first instance in two object types both have the IID 0, the second 1, and so on. Therefore the IID neither identifies a unique instance like the UID, nor does it persistently refer to the same instance (if IID 0 is destroyed, the next instance becomes IID 0). However, it can be useful for advanced users taking advantage of object expression indexing and the Pick Nth instance system condition.