Any delay in the multiple-line system will stop the line completely, while a delay in a single line might just delay one shopper.

WSJ: Find the Best Checkout Line

The problem is that the COD system creates a delay in payment.

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Failure to pick a system or a delay in implementation could allow foreign companies to grab a head start by patenting Asian medicines in their own countries.

CNN: SPECIAL REPORT: HEALTH

Researchers say it could help heart failure patients with a "conduction delay" -- in essence, a faulty electrical system in the heart.

CNN: Pacemakers found to help heart failure patients

The NAO report also casts doubt on the MoD's claim that the new carrier-based strike force will be fully operational by 2020, saying a decision to delay investment in Crowsnest, a helicopter-based early warning system, means it will be two years late.

BBC: Carrier fighter jet U-turn cost ?74m, says audit office

Subscribers to the service can request content live, with a slight delay, or schedule the system to record it for them in advance.

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Mr Fender, chair of the Transport for Greater Manchester (TfGM) committee in charge of Metrolink, said the delay had been caused by a tram management system not being available "within the prescribed timeframe".

BBC: Metrolink from Manchester to Droylsden to open in February