Use this end point to request a mobile notary for a wet_only, hybrid or hybrid_with_enote closing. The order is placed on the closing's signing appointment, which must already have a date, a time and a complete street address; set them with PATCH /appointment first, otherwise the request is rejected with 422. The body carries order details only. client_id and product_id are optional only when your company is linked to exactly one scheduling client with exactly one signing product. Full eClosing (remote online notarization) closings are not supported here; convert the closing to hybrid or hybrid_with_enote first. Requesting a notary while an order is already open returns 409. The response has the same shape as GET /notary; subscribe to notary.order_created and notary.assigned to follow the order.