age group
The age band of wearer an apparel item is cut and graded for (newborn, infant, toddler, kids, adult) — the other half of the intended-wearer DEPARTMENT, read together with gender (a boys' tee = male + kids, a baby-girl onesie = female + infant). Like gender it is an IDENTITY discriminator, not a buyable facet: a kids' cut and an adult cut of the same design are distinct products on different grading scales, never buy-box versions of one product. Grouped in the `identity` concern, so by the derived-axis rule it is NOT axis-eligible. Distinct from `size` (the chosen size within one age band) and from `size_system` (the scale that size is expressed in). Values follow the composition corpus (Google Merchant age_group).
Age group is answered with one word chosen from the age groups list — the same word shared across every product that uses it.
It belongs to identity — who and what it is.