[FMadera]

Rev,

You'll want to know the following: (paraphrased)

The libero must have a jersey that is immediately recognized from all angles by all members of the officating crew (especially the tracker) as being in contrast color-wise from his/her teammates.

The libero may only replace a back row player, and must do so between the attack line and end lines extended. These replacements do not need an official's ok (except at the beginning of the match, which I'll get to later). These replacements also are NOT substitutions, and do NOT count toward a team's 18 substitution limit.

The libero may not complete an attack when the ball is contacted while entirely above net height.

The libero may not set a ball while in the attack zone that is subsequently attacked while entirely above net height.

The libero may not serve, block, or attempt to block.

The libero may not replace at the beginning of the match until after the umpire has checked the lineups and given the ok to enter. That does not mean the libero has to replace at this time, only that he/she cannot do so until this time.

The other libero thread in this forum has some situations you will want to watch out for. If you have any other questions, don't hesitate to ask.