Add a new element to a variable array, pushing existing elements upwards to make space if necessary.
If Position is higher than the last index in the array, the new element is added at the end of the array.
If Fill Spaces is specified, higher elements will only be pushed up until a non-defined element is found (which will be filled).
Note: a variable set broadcast is only done for the specified array element even if the action also causes changes in other elements.
See Also: the Variables section of the Userguide.