In any phase of a hockey game and in every location on the ice, a team must have a system rather than all skaters simply "doing their own thing" and chasing the puck. A coach must choose a forechecking style for the team and when to employ it - whether to order one, two, or all three forwards to pursue the puck in the offensive zone.
When the plan is to commit totally only one skater, this task should be for the forward who is nearest the puck. If there is any indecision, teammates must signal who the primary forechecker will be, and his job is to attack the puckcarrier by playing the body with his stick on the ice in order to steal the puck or force him to release it. The other two forwards must position themselves (one on each side of the ice) approximately at the top of the face-off circles even with the dot and be nearer their defensive end than any opponent is, unless it is determined that there is a good reason for an offensive commitment, and this facet depends upon the coach's system.
If there are two forwards totally committed to forechecking, the first acts in the same fashion as described above while the second would determine his duty based upon the success or failure of his forechecking teammate. If the puck eludes the first forechecker, this player would swing back into action to become now the second forechecker as the heretofore second forechecker becomes the primary one. The roles are simply reversed. The third forward would assume a position on the far side of the ice as written in the second paragraph and perform as stated.
If all three forwards are instructed to commit themselves to forechecking, the duties of the two nearest forecheckers would be to attack fully the puckcarrier and/or to anticipate where the puck might travel, while the third should be ready instantly to harass the puckcarrier if the first two forecheckers fail to interfere with the opponent's breakout. In the meantime, the first two forecheckers would swing back into action.
Whenever players are in the offensive zone with the opponent in possession of the puck or it is exposed with the opponent likely to regain possesssion, the forechecker(s) should act defensively. If, at any time, the forecheckers gain control of the puck (force a complete turnover), they now become offensive attackers who should work to create scoring chances. If any forechecker in a one or two-man system separates the puckcarrier from the puck, which then is exposed in a 50-50 situation, the others must determine if the circumstances favor an offensive thrust or if he(they) should be defensive - the decision being based on the score, time remaining, etc.. Theoretically, one's duties in the offensive zone could continue to change frequently from forechecking to attacking. If the forechecking fails to prevent the opponent's breakout, the forwards should quickly transition into their backchecking system in order to combat the attack.