Handbook for Match officials, 10.3.1:
The server is required to throw the ball “near vertically” upwards and it must rise at least 16 cm after leaving his or her hand. This means it must rise within a few degrees of the vertical, rather than within the angle of 45° that was formerly specified, and that it must rise far enough for the umpire to be sure that it is thrown upwards and not sideways or diagonally. In Diagram 10.3.1.1 services B and C are acceptable, whilst A and D are not. The height of the toss is also a factor in determining whether the toss is near vertical. In Diagram 10.3.1.2, the ball is projected from, and struck at, the same place, but service A is a fault, whilst B is acceptable.
Hier ist der Link zum Handbuch:
https://ittf.cdnomega.com/eu/2019/08...th-Edition.pdf
Der Absatz und die dazugehörigen Zeichnungen sind auf Seite 15.