teitbite yes, I am logged in a as a Super User.
The reason we post and keep hidden is for sales of merchandise for different events. Quite often the merchandise sales are cut off before the event registration closes. We could turn those fields off (unpublish them) but if we do that then those fields are not downloaded when exporting the .csv files. The only fields that are downloaded during the .csv export are fields that are published. The only way to have those fields exported, yet not visible to the user because the sales window has closed, is to mark them as hidden.
We also have a few events where we have a notes field that is hidden, this allows the event Admins to make notes about a registration or special things that need to be done for that participant before the event happens and of course these notes or special requests are not to be seen by the registrant but they can be added to the .csv download and passed on to the people that need to do something with them.
So while the "Hidden" field seems strange, it actually has a very important roll to play in the DT Register system.
The link and login information has been added above.