There are two types of paper you can submit: refereed (academic stream), or unrefereed (industrial stream). Refereed papers will be reviewed by experts against criteria for scientific papers, such as originality and technical quality, and then will be accepted to or rejected from the academic stream. If you are not familiar with scientific papers and their reviewing process, you may want to read guides like How To Get Your SIGGRAPH Paper Rejected, How to Write an Informatics Paper or The Researcher's Bible.
For the final camera-ready copy, the format should be A4 with at least 25mm of margins, unnumbered.
June 30: Deadline for draft papers (academic stream) August 3: Notification of acceptance of academic stream papers August 31: Deadline for camera-ready paper submission September 12-14: Forth200x meeting September 14-17: EuroForth 2018 conference