The NCAA Football Rules Committee has approved rules changes for the 2000 season designed to protect defensive players from potentially harmful blocks and to curb offenses from gaining an advantage over defenses through the use of substitution practices.

The committee conducted its annual meeting February 14-15 in Indianapolis.

One of the approved changes expands the definition of an illegal block to include any high-low or low-high combination block by any two offensive players when the initial contact clearly occurs beyond the neutral zone. Previously, such a block could have been considered legal if the contacts were simultaneous.

The committee also approved changes regarding blocking below the waist by offensive players set wide in a formation or in motion. Previously, offensive players positioned more than seven yards in any direction from the middle offensive lineman at the snap, or in motion toward the ball at the snap, were prohibited from blocking below the

waist toward the original position of the ball, commonly referred to as a crack-back block, behind the neutral zone and within five yards beyond the neutral zone.

Now, the prohibition includes offensive players in motion in any direction, and the area in which such a block is illegal increased to include the neutral zone and 10 yards beyond.

"These two changes are evidence of the importance the committee, and the NCAA as a whole, places on student-athlete safety," said committee Chair Chris Ault, athletics director at the University of Nevada. "Defensive players often do not see opponents preparing to deliver these kinds of blocks, which can leave them in a most vulnerable position."

Offensive teams, while in the process of substitution or simulated substitution, are now prohibited from rushing quickly to the line of scrimmage and snapping the ball with the obvious attempt to create a defensive disadvantage.

The first time officials detect such an action, play will be stopped when the ball is snapped and the offending team will be penalized five yards for delay of game. In addition, the head coach will be warned that any further use of the tactic will result in a stoppage of play and a 15-yard penalty for unsportsmanlike conduct.

"More offenses are using multiple substitutions, and those substitutes are coming onto the field just before the snap, which is not within the spirit of the rules," Ault said. "Defenses were at a distinct disadvantage because they had little opportunity to make necessary adjustments.

"We anticipate that having the possibility of being penalized will encourage offenses to abide by the spirit of the rules and eliminate such last-second personnel changes."

Among the other rules approved by the committee are:

* Allowing any two defensive players to wear a four-inch by 12-inch white towel without markings attached to the front belt.

* Prohibiting a defensive player(s) aligned in a stationary position within one yard of the line of scrimmage from making quick and abrupt actions that are not part of normal player movement in an obvious attempt to cause an offensive player(s) to foul.

* Allowing a passer who is five or more yards toward the sideline from the original position of the ball at the snap to throw the ball so that it lands beyond the neutral zone to avoid loss of yardage without penalty.

The committee identified illegal blocks, substitutions as an attempt to deceive and teams showing respect for opponents as points of emphasis for 2000.