While the textual representation of leap seconds is defined by BIPM as "", some computer operating systems derive this human-readable representation from a binary counter giving the number of seconds elapsed since an epoch ; for instance, since in Unix machines. This counter has no indicator that a leap second is occurring. Some computer operating systems, in particular Linux, assign to the leap second the number of the preceding second sequence , while other computers assign to the leap second the counter value of the next second sequence.
Since there is no standard governing the sequence, the time stamp values can vary by one second. This may explain many flaws in time-critical systems that occur when exchanging time-stamped values. A number of organizations reported problems caused by flawed software following the June 30, , leap second. Among the sites which reported problems were Reddit Apache Cassandra , Mozilla Hadoop ,  Qantas ,  and various sites running Linux.
On November 28, , this happened. At midnight, the receivers with this firmware reported November 29, for one second and then reverted to November 28, Older Trimble GPS receivers had a software flaw that would insert a leap second immediately after the GPS constellation started broadcasting the next leap second insertion time some months in advance of the actual leap second , rather than waiting for the next leap second to happen. This left the receiver's time off by a second in the interim. The advance announcement of the leap second is applied as soon as the message is received, instead of waiting for the correct date.
A workaround has been described and tested, but if the GPS system rebroadcasts the announcement, or the unit is powered off, the problem will occur again. On January 21, , several models of GPS receivers implemented the leap second as soon as the announcement was broadcast by GPS, instead of waiting until the implementation date of June The NTP packet includes a leap second flag, which informs the user that a leap second is imminent.
This, among other things, allows the user to distinguish between a bad measurement that should be ignored and a genuine leap second that should be followed. It has been reported that never, since the monitoring began in and whether or not a leap second should be inserted, have all NTP servers correctly set their flags on a December 31 or June Four different brands of marketed navigational receivers that use data from GPS or Galileo along with the Chinese BeiDou satellites, and even some receivers that use BeiDou satellites alone, were found to implement leap seconds one day early.
The problem was found to exist in commercial simulators that are used by manufacturers to test their equipment. The effect of leap seconds on the commercial sector has been described as "a nightmare". Despite the publicity given to the leap second, Internet network failures occurred due to the vulnerability of at least one class of router. The leap second also affected the Altea airlines reservation system used by Qantas and Virgin Australia. Cloudflare was affected by the leap second.
Its DNS resolver implementation calculated a negative number when subtracting two timestamps obtained from the Go programming language 's time. Now function, which then used only a real-time clock source. There were concerns that farming equipment using GPS during harvests occurring on December 31, , would be affected by the leap second. The most obvious workaround is to use the TAI scale for all operational purposes and convert to UTC for human-readable text.
Grid automation is planning to switch to TAI for global distribution of events in electrical grids. Instead of inserting a leap second at the end of the day, Google servers implement a "leap smear", extending seconds slightly over a time window prior to the leap second. It has been proposed that media clients using the Real-time Transport Protocol inhibit generation or use of NTP timestamps during the leap second and the second preceding it.
From Wikipedia, the free encyclopedia. Extra second inserted to keep civil time in sync with the Earth's rotation.
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Archived PDF from the original on October 23, Retrieved October 23, I think I will benefit as much from the discussion as I think I can contribute based on our experiences in trying to design benefits in a rather complex environment — with a large private health sector and many medical insurance companies and administrators.
Health benefit plans define the services that will be available within a health system and should cover all levels of care, from community based services through to highly specialised care. This is important for at least two reasons: a certainty on what services are offered; and b ensuring that these services are funded.
What have been the challenges in development of the benefits package in South Africa? An initial challenge has been the wide range in standards and guidelines relating to service delivery in South Africa not just across the public and private sector, but also across disease areas. We are addressing this as a priority to ensure a common understanding of acceptable quality of care prior to costing.
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Other challenges include: a availability of data, including epidemiological data, b limited or fragmented health technology assessment capacity in the country; b political pressure to include all services currently available — even in the context of limited resources; c and the designing of a transparent process by which to prioritise services and revise the package over time.