The file extension UDC identifies so-called user-dictionaries, ie user dictionaries of the DTP (Desktop Publishing) solution Adobe InDesign. With InDesign, for example, you can create print templates and layouts for print products such as flyers, catalogs or brochures.
UDC files can be created in InDesign via 'Edit-> Preferences-> Dictionary'. They contain added words as well as redefined words of the standard dictionary. You can also import UDC files from older InDesign versions into this menu.
Most often resolving problems with opening UDC files is very simple. Just install an appropriate program that supports such files. All of the listed programs support UDC files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of UDC files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate UDC files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Adobe InDesign applications is not on the list, select "Browse" option in order to manually locate the directory where Adobe InDesign has been installed.
Sometimes problems with opening UDC files may not lie with the application itself, but can arise due to other causes, such as: