There is only one file type that uses the .NUD extension:
Now Up-To-Date Calendar File
Calendar created by Now Up-To-Date, an application that organizes calendar activities; contains events separated into day, week, month, and year views; includes event information such as the title, date, time, priority, and type.
To create the NUD file, select, name the file, choose the save location, and click .
To import an .ICS file, select, select the ICS file, and click .
Updated: March 31, 2014