Abstract: Aggregates of sets of identification tags are described, such as may be used on animals, such as mice or rats, affixed to ears or attached otherwise to an animal. A set may comprise from two to five patterns. An aggregate may comprise one to five sets. Patterns comprise a perimeter with an interior contrasting field, optional contrasting shapes within the field, and an optional contrasting shape core within a shape. Simple shapes may be squares, circles, or triangles. Shapes are selected for maximum machine readability. A pattern may have from zero to three shapes in its field. Patterns within sets are selected for maximum differentiation between the patterns in the set. Aggregates are selected based on the number of different sets required. Identification tags may be used to uniquely identify animals in a cage. Shown are specific patterns for embodiments of devices, systems and methods.