There are no specific guidelines regarding the length of the slides. The idea is to upload a presentation/poster-like material to the meeting page so that the participants may read about your work and provide comments/questions prior to the meeting and have discussions during the WG session. Please feel free to upload any additional material if you find necessary.
How to upload your talk to the meeting website
1) Click on the Timetable tab in the left-hand menu on the conference homepage and scroll down to find your contribution.
2) Click on the pencil icon, this will open a drop down menu.
3) Select 'Material Editor', this will open a new window with the possibility to upload your material to meeting page.