A TDL file stores data in a text format with blocks of information separated by tabs. It is similar to a .CSV file, but uses tabs to delineate data instead of commas. TDL files can be imported into most spreadsheet programs.

Tab delineated files may also use the .TSV extension.

Tasklist created by ToDoList, an application that allows users to organize their tasks and overall schedule; contains tasks, dates, duration, priority, alarm reminders, and other scheduling data.

ToDoList can visualize tasklists as a Task Tree, List View, Calendar, Gantt Chart, and Statistics. The application can also export tasklists to a variety of file formats, such as .HTML, .ICS, .GAN, and .MM.