What are the actions

Can anyone explain the following.
1)skirmish line order
2)Fire by Rank
3)Volley fire. Present

1) Skirmishers are infantry or cavalry soldiers stationed ahead or alongside a larger body of friendly troops. They are usually placed in a skirmish line to harass the enemy.

2) Procedure
Front rank readies and fires.
Front rank kneels down and begins to reload.
Second rank fires once front rank has finished kneeling.
Second rank kneels down and begins to reload.
Repeat steps 1-2 until all of the ranks in the square have been exhausted.
All ranks stand back up to finish reloading process.
Repeat the entire process.

3) Volley fire a method of small arms or artillery fire in which all of a given units weapons are fired simultaneously so as to maximize the effect on the enemy.