What are the net and centre-line violations in Beach Volleyball?

Section 7: Violations & Penalties

Double contact: The ball visibly contacts a player's body in two successive movements (particularly scrutinised on overhead sets). Results in loss of rally.
Carry / lift: The ball is caught, thrown, or comes to rest momentarily on any part of the body. Results in loss of rally.
Four contacts: The team uses more than 3 contacts to return the ball. Results in loss of rally.
Open-hand tip: Using fingertips to softly direct the ball over the net. Results in loss of rally.
Illegal set over the net: Setting the ball over the net at an angle not perpendicular to the setter's shoulders. Results in loss of rally.

Net touch: Any player contact with the net during play results in loss of rally. Exception: incidental contact with hair, or contact that does not affect play and occurs away from the ball action.
Reaching over the net: A player may reach over the net to block only after the opponent has completed their attack hit. Reaching over before the attack is interference — loss of rally.
Penetration under the net: A player may partially cross under the net into the opponent's court as long as they do not interfere with the opponent's play. Complete crossing (both feet or any body part fully in the opponent's court) is a fault.

Foot fault: Server steps on or beyond the end line before contacting the ball. Loss of rally.
Service order violation: Serving out of the team's established alternating order. Loss of rally and correction of service order.
Service delay: Failing to serve within 5 seconds of the referee's whistle. Loss of rally.
Screen: A player or team intentionally obscuring the server from the receiving team's view is prohibited, though screening is rare in beach volleyball with only 2 players.

The FIVB uses a progressive sanctions system for misconduct:

Warning (yellow card): No penalty, recorded for the match. Verbal warning for minor misconduct.
Penalty (red card): Point and service awarded to the opponent. For repeated or more serious misconduct.
Expulsion (yellow + red cards together): The player is removed for the remainder of the set but may return for subsequent sets.
Disqualification (yellow + red cards separately): The player is removed for the remainder of the match. The team forfeits.

Double contact: The ball visibly contacts a player's body in two successive movements (particularly scrutinised on overhead sets). Results in loss of rally.
Carry / lift: The ball is caught, thrown, or comes to rest momentarily on any part of the body. Results in loss of rally.
Four contacts: The team uses more than 3 contacts to return the ball. Results in loss of rally.
Open-hand tip: Using fingertips to softly direct the ball over the net. Results in loss of rally.
Illegal set over the net: Setting the ball over the net at an angle not perpendicular to the setter's shoulders. Results in loss of rally.

Net touch: Any player contact with the net during play results in loss of rally. Exception: incidental contact with hair, or contact that does not affect play and occurs away from the ball action.
Reaching over the net: A player may reach over the net to block only after the opponent has completed their attack hit. Reaching over before the attack is interference — loss of rally.
Penetration under the net: A player may partially cross under the net into the opponent's court as long as they do not interfere with the opponent's play. Complete crossing (both feet or any body part fully in the opponent's court) is a fault.

Foot fault: Server steps on or beyond the end line before contacting the ball. Loss of rally.
Service order violation: Serving out of the team's established alternating order. Loss of rally and correction of service order.
Service delay: Failing to serve within 5 seconds of the referee's whistle. Loss of rally.
Screen: A player or team intentionally obscuring the server from the receiving team's view is prohibited, though screening is rare in beach volleyball with only 2 players.

The FIVB uses a progressive sanctions system for misconduct:

Warning (yellow card): No penalty, recorded for the match. Verbal warning for minor misconduct.
Penalty (red card): Point and service awarded to the opponent. For repeated or more serious misconduct.
Expulsion (yellow + red cards together): The player is removed for the remainder of the set but may return for subsequent sets.
Disqualification (yellow + red cards separately): The player is removed for the remainder of the match. The team forfeits.