Aim is what the Irish government use to trace the movement of animals. NAS uses aim to trace where animals came from (usually a farm to a mart) and then trace where they are going (from the mart back to a farm)
Each animal has a unique ID number, in NAS this is shown as an eartag number
here is an example of a movement as shown in NAS, the eartag number is a unique animal, the move from section is where the animal has come from, and the move to is where its going,. the numbers in those sections are holding numbers and they are also unique to a farm or mart, the Irish government use these numbers as a reference when referring to a farm or mart for quick lookup.