[threeten-dev] Format of a negative TemporalAmount (Duration/Period)

[Ben Fortuna]

Hi,

I have recently started to replace a custom iso8601 implementation with the
jsr-310 backport. I notice that negative durations/periods are formatted
like so:

P-2D

However in other specifications (e.g. iCalendar -
https://tools.ietf.org/html/rfc5545#section-3.3.6) they make reference to
(supposedly iso8601) durations formatted as follows:

-P2D

I have found other references to iso8601 that place the negative sign at
the start of the string also, eg:

http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a003169814.htm

I was wondering if you could explain the reason behind the difference in
formatting negative values, or point me to further discussion (or an
RFC/specification) on this matter. Many thanks.

regards,
ben