Creates an order directly in Syntech's accounting system.

• reference — your customer reference assigned to the order.
• backorder — yes or no. If no and stock is insufficient at your location, the order is not created (RC9). If yes, the order is created and backordered items are listed in the response.
• shipping.type — delivery or collection. Syntech shipping fees apply to orders below the free-shipping threshold.
• shipping.location — for delivery: a full address object, validated against Google Geolocation (RC10 on mismatch). For collection: the string cpt or jhb.
• lineitems — a SKU → quantity map. Prices come from your Syntech reseller account.