Vorlage:Studienplan Freie Wahlfächer

The curriculum leaves 4,5 ECTS for courses that can be chosen nearly completely freely. There is also a list of free electives in TISS, however, you may use almost any course for this category. The only formal requirements are:

• it's offered by an established university (any university, not necessarily TU Wien)
• you'll get a certificate with a grade and a number of ECTS points
• it's not equivalent to a course you have to do as a part of the program.

In practice, this means you can do almost anything you want to earn these credits, e.g. language courses, art focused courses, introductory (or advanced) lectures from other subjects,... To get some inspiration, also see the courses offered by Uni Wien