What are external tasks?
Tasks from different subprojects can be linked together, forming a predecessor/successor dependency. When you open one of the subprojects in application, all of the predecessor tasks from other subprojects will be shown next to the local tasks in the project being opened. They appear with different bar/box style and font in the different task views, e.g. in grey color, so they can be visually distinguished from the local tasks. These tasks are called External tasks.