I'm seeing a weird difference in behavior between R versions 3.0.2 and 3.1.0.  Consider this session from version 3.0.2:

> secs = c(-6327530133, -632753013, -63275301, -6327530, -632753, -63275, -6327, -632, -63)
> class(secs) = c('POSIXt', 'POSIXct')
> secs
[1] "1769-06-27 11:44:27 EST" "1949-12-13 06:16:27 EST" "1967-12-30 10:31:39 EST" "1969-10-19 14:21:10 EDT"
[5] "1969-12-24 11:14:07 EST" "1969-12-31 01:25:25 EST" "1969-12-31 17:14:33 EST" "1969-12-31 18:49:28 EST"
[9] "1969-12-31 18:58:57 EST"
>

This looks pretty good but if I run the exact same statements on version 3.1.0, I get a different timezone for the first time:

> secs = c(-6327530133, -632753013, -63275301, -6327530, -632753, -63275, -6327, -632, -63)
> class(secs) = c('POSIXt', 'POSIXct')
> secs
[1] "1769-06-27 11:48:25 LMT" "1949-12-13 06:16:27 EST" "1967-12-30 10:31:39 EST" "1969-10-19 14:21:10 EDT"
[5] "1969-12-24 11:14:07 EST" "1969-12-31 01:25:25 EST" "1969-12-31 17:14:33 EST" "1969-12-31 18:49:28 EST"
[9] "1969-12-31 18:58:57 EST"
>

I've never even heard of LMT before!!  I found a page on Wikipedia (http://en.wikipedia.org/wiki/Local_mean_time) that talks about "local mean time" which was used in the 19th century before standard times were adopted.

Is this a bug or a deliberate change in R 3.1.0?

John


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