Hi

The practical problem with any change to leap seconds is transition from what 
we have
to the “new system”. Anything other than dropping them altogether involves a 
*lot* of 
coordination. You pretty much have to pick a date and bring everything onto the 
new
standard then. For testing purposes your time sources should “advertise” the 
new 
information ahead of that date. As a practical point, that means a new field in 
the data. 
In the case of GPS and other space based systems, that’s not going to happen. 

The alternative is to have a “magic date” and a pre-defined set of dither bits 
for the 
next year or two after that. Yes that’s a mess on top of a mess. It does allow 
people to
roll out a patch that can be tested ahead of time. They can then transition to 
the full
blown approach. If you think about the amount of time needed to do this … two 
years
may not be enough …

This indirectly gets into the systems question of: How early *do* you announce 
the dither
bit for a given month? There are systems that *do not* get their leap second 
information 
from broadcast or live network sources. You would have to put out the pattern 
early 
enough to accommodate their “pipeline”. If that involves manually loading files 
… yikes. 

Bob


> On Jul 22, 2016, at 4:44 AM, Martin Burnicki <martin.burni...@burnicki.net> 
> wrote:
> 
> Tom Van Baak wrote:
>> Time to mention this again...
>> 
>> If we adopted the LSEM (Leap Second Every Month) model then none of
>> this would be a problem. The idea is not to decide *if* there will be
>> leap second, but to force every month to have a leap second. The IERS
>> decision is then what the *sign* of the leap second should be this
>> month.
> 
> Although this approach sound good, it would cause major problems for
> users of the German longwave transmitter DCF-77. The data format only
> has a "leap second pending flag", which means a leap second is to be
> inserted. AFAIK there is no spec to announce a negative leap second via
> DCF-77.
> 
> Martin
> 
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