Level 2.5 Teletext part I

Level 2.5 Teletext is an extension to the original teletext standard where packets > 24 can be used to, amongst other things, define new colours maps and dynamically redefine character sets (thus giving access to high-resolution graphics).

Not many broadcasters use Level 2.5, but ZDF do in a limited capacity:

The standard Level 1.5 view.  But if your set supports it...

...a few seconds later you get the Level 2.5 version