How the model grew, in 15 milestones
Each dot is a card, in its area's box and in the color of its status at that milestone. Surveys of IATA's public
material add candidate rules, mostly amber because the material leaves them to the business; writing an area in Lean
turns its rules magenta and its guarantees green, or red where an example shows the rule breaking a guarantee.
Click a dot to open its card.
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The pilot 0:00 First survey 0:08 Starting small 0:14 Foundations 0:18 Second survey 0:24 Each area in Lean 0:33 An independent review 1:00 The fixes 1:07 Where it stands 1:15 A film of the graph growing card by card over the 15 milestones, in
9 steps. Each step stops on its last frame. The step control below goes through the milestones one at a
time.
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Core concepts 8 Currency Money Adding money Instant Passenger Principal Classification Public is the lowest level Pilot offers and orders 12 Offer item Offer Delivery state Delivery event Order item Order Rejection Accepting an offer Delivery transitions Order price is the sum of the items Expired offers are rejected Delivered services cannot be cancelled Pilot payments and refunds 5 Payment Refund Totals paid and refunded Accepting a refund Refunds never exceed payments Order structure 21 Order structure Services that hold value Order item status Order status Offer items for passengers and segments Creating an order from an offer One order item per offer item Order item IDs are unique One service per passenger and segment Active items are those holding value Cancelled items as the guide defines them Closed items as the guide defines them Active items are never closed Active items are never cancelled Opened orders are those holding value Closed orders as the guide defines them New orders are opened Orders are never both opened and closed Each item has exactly one status Every order is opened or closed Order items are not split Payment 43 Payment time limit Paying with several methods Paid order item Payment status and its moves Unpaid item at its time limit Surcharge on each payment method Applying a payment outcome Accepting a payment Amount charged across methods Effects of a payment outcome Failed payment leaves items unpaid Commitment only when nothing due A failed method fails the payment A payment succeeds when every method succeeds A payment is pending while a method is pending Only successful payments pay Outcomes of pending transactions are recorded Other methods keep their outcomes Settled payments under the final reading Paid items lose their payment time limits Failed and pending payments change nothing Items a payment does not cover are unchanged Unpaid items are removed at their time limit Pending payments fail at the time limit Paid items are not removed Items before their time limit are unchanged Removal to REMOVED leaves no value No payment at or after the time limit Each method is charged its amount plus its surcharge Requested amounts add up to the price Time limit on unpaid items Settled payments keep their status Removed items hold no value Committing to pay nothing Refunds across payment methods No payment after the limits Allocating a payment across items Combinable payment methods Quoted surcharge at payment time Refundable payment surcharges Refund as a negative payment Retrying a failed payment Paying with a voucher Change and cancellation 44 Cancelling an order Changing an order item Price differential of a change Penalty larger than the refund Paid or partly paid orders need an offer Amounts due to and by the airline Money recorded on an order Penalty netted or charged separately Unpaid orders are cancelled at once Kept services keep their references Originals of kept services are transferred Services not kept are cancelled Changes keep item references distinct Mixed currencies are rejected Type code names a collection Type code names a refund or a value store Value kept for later use is typed Reusable Netted penalty gives one amount Separate penalty is added to the amount due Collecting the whole penalty keeps the formula Settling adds to payments and refunds Settling records penalties and forfeits Waiving the excess penalty leaves nothing owing Due amounts net to the difference Order balance after servicing Transferred originals hold no value Orders cancelled at once are closed Cancelling leaves the customer owing nothing Cancellation offers stay within payments Transferred services keep the order balanced Stored value stays in its order Change accepted before payment Full cancellation keeps no residual Removing one passenger from an item Reusable amount on cancellation Settling money the airline owes Value store time windows Stored value is used once Name change through an offer Changes made without an offer Full cancellation equals item cancellations Stored value belongs to payer Penalties and forfeits persist Refund waits for separate penalty Delivery 36 Delivery status Moves between delivery statuses Final delivery statuses Held value after cancellation Expiry of an unclaimed service Passenger no-show Services that end without delivery Suspending and resuming a service The pilot's delivery states in ONE Order Ending a service from another area Suspended services Confirming a requested service Payment readies a confirmed service Delivering a paid service Cancellation before delivery Delivery prevented by outside constraints Delivery failed by the airline or its provider Suspending a service records where it was Lifting a suspension returns the service Cancelling a suspended service Other events follow the table Payment before delivery when the undecided moves are refused No event leaves a final status Every service can reach a final status Closed orders keep their delivery statuses Every area moves delivery statuses along the table Payment before delivery starts Orders whose services are all final are closed Refunds while delivery is in progress Who sets each delivery status Refund after a failed delivery Seller told of status changes Announced future delivery status No changes after closing Transfer keeps delivery status Delivery milestones and status Offers and prices 53 Price guarantee at an instant Accepting after the guarantee lapses Payment time limit at creation Restriction rule in force Refund owed on voluntary cancellation Time limits of a new order Voluntary change under the rule in force Totalling a price from its parts Offer expiry ends other limits Voluntary change under a restriction No price guarantee without a limit Price guaranteed before its limit Inventory guaranteed before its limit Guarantee ending at its instant New order matches ONE-001 Payment time limit from a duration Payment time limit from a fixed instant Price guarantee carried into the order No order after a lapse when repricing Rule in force belongs to the current stage Rule in force has started Latest started rule is in force Expired rules are not in force Forbidden changes are refused Rule's fee is the penalty No fee, no penalty Forbidden cancellation returns nothing Full refund returns the whole price Fixed refund returns its amount Refund to the original form of payment Mixed-currency prices are rejected Discount above the base is rejected Base amount after discounts Tax summary total from its entries Total from base, surcharges, fees and taxes Excluded tax from the lines Taxes on a non-refundable fare Price total from its parts Guaranteed prices only on offers that can be accepted No order at a lapsed price No order item overdue at creation Payment due at creation can be made Every stage with rules has a rule in force Nesting of guarantee time limits Consumption tax lines add up Mandatory and optional offer items Terms of a combined interline offer Currency of an offer's amounts Time limits as UTC instants Order time limits only extend Tax summary total and detail Seller margin stays outside order Offer responsible airline owns order Order creation 50 Order retention Selecting items from an offer Change against a stale version Retention after first usage Recording changes to an order Creating one order from several offers Repeated create requests Order history Order version New orders start at version 1 Each change group raises the version by one Orders kept 13 months from creation Orders kept 7 days after their items are final Unknown items are rejected Selections include the mandatory items A selection takes the items it names Offers with a mandatory item Orders hold the selection when the whole request is checked Order price when the whole request is checked Requests that select nothing are rejected Rejecting the whole request New orders are recorded against their offers Repeated requests get the existing order Repeated requests can be rejected Returning or rejecting repeats keeps one order per offer The history lists each change group once Oldest first, the history rebuilds the order Changes on the current version are applied Changes without a version are applied Rejecting stale versions Order items match the selection Atomic order creation One order per offer History rebuilds every version Order total from item prices Every order holds a mandatory item Order price is the sum of the selected items Changes on a stale version are rejected Orders holding value stay accessible Failed payment at order creation Statuses of a new order Paying for part of an order Order items in a retrieved order Read access to an order Group order limits Version tracks seller-visible changes Service IDs in an order Order ID Order owner is the offer owner Verifying distribution chain identities Ancillaries 53 Dependent service and its parent Cancelling a flight with ancillaries Dependents when a flight changes A-la-carte offer item Price of an a-la-carte selection Value of one bundled service Adding services to an order Choosing seats Dependents by reference Dependents through passenger and segment A flight is never a dependent Passenger and segment reach every ancillary An ancillary without its flight is refused Added items follow the existing ones Services that need no flight are added Named items are cancelled Items that may not be cancelled are refused Other services are kept Two readings leave no live dependent Two readings keep the dependents' conditions Two readings let a cancellable item be cancelled Every dependent gets one effect The effect follows the kind of service A moved service keeps its reference A seat the map does not offer is refused Each seat becomes its own order item Ineligible choices are refused One order item per passenger and segment Price of each a-la-carte order item Total of an a-la-carte choice Removed services are cancelled A removal returns the services' shares Ancillary needs a flight service One passenger per seat One seat per passenger per segment Every ancillary reaches its flight No live dependent of a cancelled flight Dependents keep their own conditions A cancellable item can be cancelled Moved seats on the new flight One order item per a-la-carte offer item A removal returns no more than the bundle price Removing a whole bundle returns its price Dependent impact shown before acceptance Dependent service lost by airline change Seat needs an eligible price point Bundle of services Pick M of N price Free seat creates a zero-priced item Pooled baggage allowance Extra baggage weight Matching a taxonomy criterion Removing a passenger and dependents Airline change 39 Consequence of a missed time limit Changes that require a customer choice Voluntary and involuntary change Seller follow-up action Answering a change notice Declining an airline change Cancelling a flight without re-accommodation Re-accommodation before the seller answers Change applied before seller response A notice without follow-up actions needs only acknowledgement An offered action answers the notice Answers are offered actions taken in time Unanswered notices stay pending until they lapse Recorded contact stops the time limit The earliest time limit decides the consequence No time limit, no consequence No consequence before the time limits Cancel is priced as a cancellation Reshop is priced as a change Waived fees leave no penalty Services on a cancelled flight are cancelled Other flights are unchanged Order items keep their references and prices Refunds stay within the item's price A change awaiting Accept leaves the order as it was New flights for every passenger at the same price Waiting for Accept keeps the original item Penalty when declining an airline change Refund for a cancelled flight Paid status after re-accommodation Pending follow-up actions Cancelled service in an active item Price of reshopping after airline change Notices are resolved before departure Original item kept while Accept is pending No live service is left on a cancelled flight Unacknowledged change notice Repricing after waitlist confirmation Who is told of a change Accounting 68 Settlement value of a service Commission on an item Net clearance amount Clearance status Allocating a short remittance Billing by service providers Accounting for paid services Accepting a clearance Total of a clearing Net position of a party Billing after delivery Billing limited to delivered services Revenue recognized at final status Commission cleared exactly once Clearing total Bills from the delivering provider only Bills for delivered services accepted Delivered services earn revenue Money balance when cancellation amounts are checked Refunds within payments when cancellation amounts are checked Checking a cancellation's amounts Fixed commission Percentage commission to within a cent Several commissions add up Commissions in another currency Percentage commission within its base Seller collects and nets the commission Seller collects, commission cleared separately Airline collects Refund through the seller Refund clearances without full recall Repeated clearance ID Repeated payment without signatures Accepted clearances recorded One clearance per payment when signed data is checked Cancelling an accepted clearance Settling a clearance in full Settling a clearance in part Writing off a clearance EasyPay out of a remittance payer's clearing Net position formula Settlement payees Remittance payers EasyPay out of the payer's position Positions sum to zero with the EasyPay provider Clawed-back amounts unsettled again Short remittance within what is owed Each payee's clearances oldest first Proportional shares Oldest first across payees Transfer of Funds allocates the whole payment Money balance of an order One clearance per payment commitment Net position per remittance date Settled and unsettled clearance amounts No liability left at a final status Refunds within payments Seller never pays for a refund Clearing totals are never negative Whole payment allocated One allocation for a short remittance First accounting posting after payment Cancelling a clearance Netting on a change Order of accounting postings Commission from offer to order Requesting a clearance Clearance request matches the order Each milestone is a tagged commit, milestone/<name>; its snapshot is in
history/ . The film follows the
motion brief and is drawn from the same snapshots.