NBA vice president of basketball operations Stu Jackson confirmed Wednesday that several new rule interpretations will be a point of emphasis for the league's referees when the regular season begins on Dec. 25.

"Rip-through" moves, in which an offensive player swings the ball into a defender's outstretched arm and then attempts a shot once he has created contact, will be considered non-shooting fouls if the contact begins before the offensive player starts his shooting motion.

Also, on drives to the basket, a shooting foul will be called only if contact occurs after the offensive player has begun his shooting motion, not after he has initiated his leap toward the basket.

"Certain types of contact involving the shooter were all being called in his favor," Jackson said. "It doesn't look good for the game. There was a strong feeling that those types of plays were creating an ill-advised reward for the shooter, often with three free throws."

The league will also make traveling in the post and on the perimeter a point of emphasis, with a player hopping off of and landing on the same foot viewed as an automatic violation. Referees will also consider locking or clamping an opponent's arm or hand under the basket while battling for a rebound and discontinued or hesitation dribbles as automatic violations.

Several rule changes will also be introduced, most to shorten the overall length of games and speed up the final minutes of a contest:

• Substitutions will only be allowed before the final free throw of any trip to the line that is not for a technical or flagrant foul.

• Two horns will be sounded 15 seconds apart after every timeout. Teams whose players are not moving toward the court as soon as the second horn sounds will receive a delay-of-game warning.

• Instant replay will be utilized only during full timeouts, not 20-second timeouts, when necessary.

• Whether a player's foot is on the three-point line or midcourt line will be determined by where it last touched the floor, meaning a player could have a toe on the three-point line but if he leans back on his heels before he releases the ball a successful shot would be deemed a three-pointer.

• The eight-second backcourt violation will occur when the shot clock reaches 15 seconds, rather than 16.

The last rule is necessary because the 24-second shot clock will now be equipped to show 10ths for the final five seconds and work as a "true" clock. From a technical standpoint, the old shot clock began with 24.9 seconds and expired with .9 left. Now the clock will switch from 24 to 23 seconds after .1 second has expired.

Jackson said a survey of coaches determined when the shot clock would break into 10ths.

"We didn't want to run them for the whole 24 seconds and the consensus was, from a strategy standpoint, that the final five seconds were the most valuable," he said. "Before, you could have two seconds left on the shot clock but you wouldn't know if it was 2.9 or 2.1. That makes a big difference."

Referees also will be hyper-vigilant about defenders making contact with offensive players when they're in the air and fully extended attempting to score. In most cases, expect that kind of foul to draw a Flagrant Level 2, which is two free throws, possession of the ball and the defender being ejected.

"That type of contact was a trend last season and it's really dangerous," Jackson said.

Ric Bucher is a senior NBA writer for ESPN The Magazine.