0,0,0 is a very valid coordinate - it’s the centre of the scene. If something is at 100, 0, 0 and you tell it to go to 0, 0, 0, it will move 100uus. It sounds as if you wanted the script treat an otherwise valid 0,0,0 as invalid. Would that work for you:
Another, much better imho, way is to include a flag in the Data Table entry, indicating whether this vector (or some of its components), is valid. Consider incorporating more meaningful data in the structs.