I have an Excel COM (actually .NET) add-in that I'm trying to adapt for an
international market. Part of its functionality is to display cell values
exactly as they appear in the Excel formula bar.

When testing with a French version of Excel and French locale settings, I'm
seeing a strange value for the hour format which so far has only appeared
when the cell value is midnight (00:00:00, or 12:00:00 AM in US format, or 0
in the default numeric format). It starts with "[$-F400]" when retrieved
with Excel.Application.ActiveCell.NumberFormat with a local "en-US" culture
setting, but I can't find any references to that format prefix online. The
full format is shown as "[$-F400]h:mm:ss AM/PM", although I'm not sure where
the AM/PM came from, since that cell was created with French culture
settings. Maybe it's the US settings I use to retrieve it?

Does anyone know what the [$-Fxxx] hour format prefix means and how to
interpret it? If so, I can look for it and display the time appropriately
(right now, midnight is displaying as 0). My guess is that it has something
to do with GMT, which is probably correct for my current Eastern US time zone
with Daylight Savings Time.

Another question is why it seems to be specific to time values of midnight,
at least in my testing so far.

Any help would be very much appreciated. Thanks in advance.

--
Terry Rochford