> For the complete documentation index, see [llms.txt](https://resources.atriptech.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://resources.atriptech.com/api-document/product-guides/booking/booking-overview/identifiers.md). # Identifiers {% hint style="info" %} 💬 **Need help?** If you're stuck, ask Eva in the Help Center for instant diagnostics. Ask Eva {% endhint %} Use this page when you need to keep the right Atlas API identifier at the right stage. Start here when you need to: * know which identifier each API returns * know how long each identifier stays valid * know which downstream API uses it next * avoid retrying with stale identifiers ### FAQ #### Which identifier should I keep after `search.do`? Keep `routingIdentifier`. Use it for `verify.do` in the standard search flow. #### Which identifier should I keep after `verify.do`? Keep `sessionId`. Use it for `order.do` and for `seatAvailability.do` in the standard booking flow. #### Which identifier should I keep after `getOffers.do`? Keep `OfferId`. Use it for `order.do` in the Get Offer flow. Use the same `OfferId` for `seatAvailability.do` in that flow. #### Which identifier should I keep after `getOfferPrice.do`? Keep `OfferId`. Use it for `order.do` in the fulfillment flow. Use the same `OfferId` for ancillary lookup in that flow. After `order.do`, keep `orderNo` as the main operational identifier. Use `orderNo` for payment, order query, and ticketing follow-up. #### How long is each identifier valid? `routingIdentifier` is valid for up to 6 hours after `search.do`. `sessionId` is valid for up to 2 hours after `verify.do`. `OfferId` should be treated as short-lived booking context. Refresh it when booking-critical input changed or booking was delayed. The `OfferId` from `getOfferPrice.do` is also short-lived. Use it immediately because the fulfillment flow is built for fast payment and ticketing. ### Main identifiers #### `routingIdentifier` **What it is** The route token returned by `search.do`. **Use it for** Use it for `verify.do`. **Validity** Up to 6 hours after search. **Do not use it for** Do not use it for `order.do`. **Typical failure** `202` usually means the `routingIdentifier` expired. #### `sessionId` **What it is** The verification context returned by `verify.do`. **Use it for** Use it for `order.do` in the standard flow. Use it for `seatAvailability.do` in the standard flow. **Validity** Up to 2 hours after verify. **Do not use it for** Do not reuse it after timeout. Do not use it across unrelated bookings. **Typical failure** `301` usually means the `sessionId` expired. #### `OfferId` **What it is** The offer token returned by `getOffers.do`. **Use it for** Use it for `order.do` in the Get Offer flow. Use it for `seatAvailability.do` in the Get Offer flow. **Validity** Treat it as short-lived and refresh it when the booking context changed. **Do not use it for** Do not assume it stays valid after long delays or itinerary changes. **Typical failure** If order creation fails because fare or inventory changed, refresh the offer and rebuild from the latest `OfferId`. #### `OfferId` from `getOfferPrice.do` **What it is** The short-lived offer context returned by `getOfferPrice.do`. **Use it for** Use it for `order.do` in the fulfillment flow. Use it for ancillary lookup before `order.do` when needed. Then switch to `orderNo` for payment and follow-up. **Validity** Treat it as immediate-use context. Do not hold it for delayed booking decisions. **Do not use it for** Do not treat it as a long-lived shopping identifier. Do not reuse it after the fulfillment window has already shifted. #### `orderNo` **What it is** The Atlas order identifier returned after order creation. **Use it for** Use it for `pay.do`, order lookup, payment follow-up, and post-booking flows. **Validity** Keep it for the full order lifecycle. **Do not use it for** Do not use it as a substitute for search or verify identifiers. #### `retryAfter` **What it is** The wait time returned with `HTTP 429 Too Many Requests`. **Use it for** Use it to decide how long to wait before retrying. **Validity** It applies to the current rate-limit event. **Do not use it for** Do not ignore it and retry immediately. ### Which identifier comes next? #### Standard search flow 1. `search.do` returns `routingIdentifier` 2. `verify.do` returns `sessionId` 3. `order.do` returns `orderNo` 4. `queryOrderDetails.do` returns airline PNR and ticket data #### Get Offer flow 1. `getOffers.do` returns `OfferId` 2. `order.do` returns `orderNo` 3. `queryOrderDetails.do` returns airline PNR and ticket data #### Fulfillment flow 1. `getOfferPrice.do` returns `OfferId` 2. `order.do` returns `orderNo` 3. `pay.do` uses `orderNo` 4. `queryOrderDetails.do` returns airline PNR and ticket data ### Fresh-identifier rules Start earlier in the flow when these conditions apply: * `202` — run `search.do` again and get a fresh `routingIdentifier` * `301` — run `verify.do` again and get a fresh `sessionId` * `308` or inventory drift after Get Offer — run `getOffers.do` again and get a fresh `OfferId` ### Best practice Store the returned identifier together with: * request time * itinerary summary * passenger mix * current flow type * fulfillment-flow marker when your integration tracks one This makes expiry and retry decisions easier. ### Related pages * [Booking Overview](/api-document/product-guides/booking/booking-overview.md) * [Search](/api-document/product-guides/booking/booking-step-guides/search.md) * [Get Offer](/api-document/product-guides/booking/booking-step-guides/get-offer.md) * [Fulfillment API](/api-document/product-guides/booking/booking-step-guides/get-offer-price.md) * [Get Offer vs Fulfillment API](/api-document/product-guides/booking/booking-overview/booking-decisions/get-offer-vs-get-offer-price.md) * [Verify](/api-document/product-guides/booking/booking-step-guides/verify.md) * [Create Order](/api-document/product-guides/booking/booking-step-guides/create-order.md) * [Get Offer Price](/api-document/api-reference/booking-apis/get-offer-price.md) * [Error Codes](/api-document/support-and-reference/troubleshooting-and-support/errors-handing.md)