Some written Indicators per the NCAA
Launch — a player leaving his feet to attack an opponent by an upward and forward thrust of the body to make forcible contact in the head or neck area
A crouch followed by an upward and forward thrust to attack with forcible contact at the head or neck area, even though one or both feet are still on the ground
Leading with helmet, shoulder, forearm, fist, hand or elbow to attack with forcible contact at the head or neck area
Lowering the head before attacking by initiating forcible contact with the crown of the helmet
There is also a whole separate category for defenseless players which these two were not.
The worst part of the rule is even with objective indicators there is subjectivity to the call depending on the officials on the field or in the booth/office. The rule itself states when in doubt to err on the side of the foul.
That would make sense if it was simply a penalty, but when it involves an immediate ejection, it should err more on the side of keeping players eligible especially in bang/bang plays. Hauck and many other coaches believe that is overofficiated and takes away from the game.