Sometimes defenders will switch their force temporarily during a play if the disc is on the sideline. This is usually done right after a pull or the red team turns it over on the sideline and blue is now on offense.
On a turn over or right after the pull, usually teams will force the flick throws. In this case it is forcing home. In this special scenario, the disc is has been turned over on the Away sideline. To prevent H1 from making a throw to the center of the field (which is the best throw in many cases), defender 5 will scream out, "FORCING LINE for 1!!!!!!"
This has to be yelled out and communicated to the rest of the team that 5 is forcing line. The rest of the phrase "for 1" tells the team to only force the thrower to throw up the line for 1 throw. After 1 throw has been completed, everyone forces the original force -- Force Home.
In this scenario, once H1 throws the disc to a cutter or H2, everyone reverts to forcing Home.
Once the throw has been made, defenders 1 to 4 begin to force Home.
The defenders can also scream out, "FORCING LINE FOR 2!" or "FORCING LINE FOR 3!" which means force the line side for 2 throws or force the line side for 3 throws. Usually, defenders will force lines for 1 throw.