Best Practice for handling timezone offsets in DTL

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Question

#DTL #HL7 #Tips & Tricks #Tools #Ensemble #Health Connect

Hi all,

My team is exploring options for handling timezone offsets in DTL and we’re wondering if there are any built-in methods available — ideally low-code or no-code solutions. Specifically, we're looking for a way to adjust timestamps based on the date and whether Daylight Saving Time (DST) is in effect.

For example, if an HL7 message has an MSH-7 value of 20250518144529, it should be converted to 20250518144529-0500 (Central Daylight Time), but if the timestamp were 20250218144529, it should be 20250218144529-0600 (Central Standard Time).

We’re fairly new to InterSystems and want to make sure we’re not reinventing the wheel if there’s already a best practice or supported feature for this.

Thanks in advance for any guidance!

Product version: HealthShare 2024.1

$ZV: HealthConnect:7.2.0-2.m1

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score 0 · Answer 1 · 2025-05-23T12:03:21-04:00

I tend to use $SYSTEM.SQL.Functions.DATEADD()

You can use this to add seconds, minutes, hours, days, etc. to date. The date/time should be ODBC e.g "2025-05-21T14:52:47.986"

There may be other ways, but this is how I do it to deal with UTC offsets.

score 0 · Answer 2 · 2025-05-23T12:09:42-04:00

This comment shows a quick way to convert to ODBC

https://community.intersystems.com/post/convert-numeric-expression202010...

You may have to tweak a little.

USER>w $tr("abcd-ef-gh ij:kl:00","abcdefghijkl",20250518144529) 2025-05-18 14:45:00

score 0 · Answer 3 · 2025-05-23T12:11:49-04:00

USER>s time=$tr("abcd-ef-gh ij:kl:00","abcdefghijkl",20250518144529)

USER>w time 2025-05-18 14:45:00 USER>s time=$SYSTEM.SQL.Functions.DATEADD("hh",-6,time)

USER>w time 2025-05-18 08:45:00

score 0 · Answer 4 · 2025-05-23T13:49:50-04:00

I am bad at full thoughts evidently: do read on timezones and DST though so you don't hit any traps - https://docs.intersystems.com/iris20251/csp/docbook/DocBook.UI.Page.cls?...

It appears in your example you need a better way to determine if you are in DST or standard. You can't just go off of month and you also might be dealing with a region that doesn't acknowledge DST.

score 0 · Answer 5 · 2025-05-23T16:44:00-04:00

Ya we know there is a lot of edge cases. We tried to handle them in our old system Cloverleaf with Tcl/Tk code, and before moving to InterSystems using Objectscript we wanted to do research on what way was best. Thank you for feedback.