What changed the last-modified time stamp of these files?

[Bill Blanton]

Though it would be the same principle, that may have to do with the network.
The server (or client) may be adjusting for the client's GMT offset when transfering
the file. Do you only see it when DST is in effect?

I know that it is happening.
I know why it is not happening. (I.E. There is no 'NTFS' filesystem present in my case.)
I don't know why it is happening! I'm not blaming anything, FAT32 vs. NTFS, Windows vs. WinNT or that network-transfers between
such systems are involved. Not even that it is not my own fault with some screwy setup somehow.

But the exact one hour difference makes one suspect 'Daylight Saving Time' (DST) is involved somehow right, but ...

... today looking for some specific examples i find this:

One machine running WinXP the other Win98SE, both using only FAT32 filesystems, both setup the same with regards to
Date/Time/TimeZone and both running with 'Auto-adjust clock for DST' disabled. But this has been happening also earlier when i've
used to leave auto-adjut enabled.

Looking at timestamps on files on CD's they show a one hour difference between the machines!, and of course this is retained when
copying the files to the HardDiskDrives.

The Win98SE machine: The WinXP machine:
------------------- -----------------
An [IE6Setup.exe] files Modified Timestamp:
2004-02-05 12:00:00 2004-02-05 13:00:00
The digital Timestamp of the same file (NOTE the reverse difference!):
2002-08-29 20:42:42 2002-08-29 19:42:42
Any file on my WinXP CD:
2001-08-18 12:00:00 2001-08-18 13:00:00
Any file on my Win98SE CD:
1999-04-23 22:22:00 1999-04-23 23:22:00

But i have saved a copy of the Win98SE installfolder to the HDD of the WinXP machine a while back and the files in there is
showing the correct timestamp of '1999-04-23 22:22:00'.

(I might misremember, but i think i've seen these one hour off timestamps also on the Win98SE side, when WinXP wasn't in the
picture.)

In conclusion, no networking involved, no FAT32 or NTFS filesystems involved.

In the case of CDs, you do have the CD file system involved. Though not mentioned
in the MSKB article previously referenced, http://support.microsoft.com/kb/129574/
the ISO 9660 (and extension Joliet) and the UDF specifications allow for saving
GMT/UTC offsets in the file's attribute field.
http://alumnus.caltech.edu/~pje/iso9660.html
http://www.osta.org/specs/index.htm

I would guess that most "CDFS"s do save UTC offsets, as they are all
a relatively modern file system.

98 appears not to use this attribute and simply displays the "time" or UTC value,
while XP makes the adjustment. Myself, I see a 4 hr difference of timestamps
between a 98 and XP system on data CDs.

US-EST=(UTC-5(+1 DST))=4.

I expect this to change to a 5 hr difference after DST ends.

Not true for FAT12 floppys. They show what is stored.

But something in the way i have setup a machine, currently the WinXP machine, it can translates the timestamps incorrectly for
display.

Interestingly, if you disable "automactically adjust for DST" in XP during
DST(I.e. Now), the timestamps shift on NTFS and "CDFS" volumes,
though of course the clock doesn't. So apparently this setting does
matter..