Does the Modified field show the date/time in UTC, or in the local timezone?

The question is about the official Zotero client, but it is prompted by an anomaly that I'm seeing in edits to a group library shared with a supervisee using Juris-M. A reference that I update shows the current local TZ time and date; but there are other refs in the library, modified by the supervisee, that show a later time.

I have checked my own machine (Ubuntu). It has the correct UTC time set in the hardware clock, and the OS is set to assume HW clock is UTC. Checking "date" at the command-line shows the correct date and time in JST, which is the machine's configured timezone. That all seems to be in order. The supervisee is using Windows 8.

Assuming my machine settings are correct, there are a couple of possibilities:

1. The clock on the supervisee machine is out of whack; or


2. There is a bug in Juris-M that affects the Modified timestamp value on one of the machines.

Which angle to pursue in debugging will depend on what value we ought to be seeing in the Modified field. If UTC should be showing there, I've either missed a problem in my own machine setup, or there is a bug in Juris-M.