[Info-vax] EU will abandon daylight savings time in 2021

[Stephen Hoffman]

On 2019-04-03 17:37:06 +0000, Jan-Erik Sderholm said:

> We have some local timestamps that has to be converted to GMT/UTC 
> before sent to another system, and these are both from "winter time" 
> and "summer time". We can of course hardcode the dates for the switches 
> and compare, but it would be nice if the rule
> could be used...

You can ask for the current timezone through various APIs, if that's 
what you're after.  But asking for the timezone setting is probably 
unnecessary.  The calls will use the current settings.

More to what you're probably after, the related calls used for fetching 
the time are the DTSS calls that were integrated with OpenVMS a while 
back (utc_ascgmtime, utc_vmsgmtime, etc), or the C standard library 
calls (e.g. gmtime), or use the system services including $GETUTC or 
SYS$TIMCON or such.

For transmitting the time, there are text-formatting routines.

Parts of the following doc are somewhere well out past wrong—lib$subx 
is not a reliable means of calcuating an interval, even as is shown for 
the OpenVMS quadword times—but this old doc will give you pointers to 
some of the available APIs:
https://www.itec.suny.edu/scsys/vms/OVMSDOC073/v73/5841/5841pro_072.html

Here are the DTSS docs:
http://h30266.www3.hpe.com/odl/i64os/opsys/vmsos84/4493/4493pro_016.html#port_api 


Related:
https://en.wikipedia.org/wiki/ISO_8601


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