I need to ask for the timezone of the server where the old DF board was located. This is required because DF uses this timezone for the time for posts and PMs etc inside the database, rather than GMT. This may not be the current timezone of the server since the database might have moved to a new host in a new location or be local for testing. I need this time to calculate the correct offset to convert dates in the database to GMT so that they will be correct in phpBB.
Currently I use the old DF boards system timezone (for displaying the times for guest users) and get the admin to set this to the server timezone before the conversion. They then have to set this back afterwards in the new phpBB forum. This works well enough, but it isn't ideal and it would be much clearer just to ask for the timezone as a setting during the conversion.