The attribute mapping table (under Stores → Configuration → Sales → Delivery Methods → ShipRateAPI Live Rates → Attribute Tag Mapping) lets you derive tags from existing product attributes without touching each product. This is useful when you already have structured data in attributes such as hazmat_class, temperature_zone, or product_category_code.

Example rules:

Attribute codes are validated against the Magento EAV catalog when you save the config. Rules with an invalid attribute code are rejected with a descriptive error before the config is persisted. At runtime, if an attribute cannot be read (e.g. it was deleted after the config was saved), the rule is skipped with a warning logged — the checkout flow is not interrupted.

Tags appear in the items[].tags array. Every connector filters out empty strings, and the API trims and lowercases each inbound tag on arrival. Deduplication is Magento-only — the Magento module merges its two tag layers and removes duplicates; the Shopify and commercetools connectors send whatever remains once empties are dropped. Duplicates are harmless either way, since matching is a membership test — though they still count toward the 20-tag limit below. A product with no tags sends an empty array.

"items": [
  {
    "sku":    "CHILLED-001",
    "name":   "Organic Milk 2L",
    "qty":    1,
    "price":  1.80,
    "weight": 2.1,
    "tags":   ["cold-storage", "perishable"]
  },
  {
    "sku":    "STANDARD-002",
    "name":   "Reusable Bag",
    "qty":    2,
    "price":  0.99,
    "weight": 0.05,
    "tags":   []
  }
]

Every rate table carries three tag fields: requiredTags, excludedTags, and matchMode. The rating engine checks them against the basket tag pool in a fixed order, before any weight, order value, or bracket logic runs.

1. Excluded tags are evaluated first, and win outright. If any tag in excludedTags appears anywhere in the basket, the table is skipped immediately with the reason tag_mismatch — requiredTags is never even read. An exclusion cannot be overridden by a required tag on the same table.
2. Required tags are evaluated second, honouring matchMode. any — the default — needs at least one required tag present in the basket; all needs every required tag present. If the basket does not satisfy them, the table is skipped with tag_mismatch.
3. A table with neither field set matches every basket — including baskets with no tags at all. That is what makes a table an unrestricted fallback.

Worked examples:

Tags are not configured as standalone rules — they are fields on a rate table. Once tags are flowing in the API payload, open Rate Tables in the admin portal sidebar, then edit (or create) the table you want to restrict. Its form carries three tag fields: Required tags, Tag match mode (shown once at least one required tag is set), and Excluded tags.

Because tags live on the table itself, they combine naturally with that table's zone, carrier, schedule window, and order value guards — a basket must satisfy all of them for the table to produce a rate. Setting the same tag as both required and excluded on one table makes it impossible to match; the Coverage Scanner flags that as an error, along with zones that have no unrestricted fallback table.