A sequence line is generally ordered for attacks by military units .
The attack begins when the drain line is crossed. It serves to synchronize the movements of the troops with one another and with the fire of the support weapons ( artillery , air forces ) in time for the start of the attack . It should be clearly recognizable in the area. If a short stop is necessary to organize the troops or for a supply, this must be made on this side of the process line. The drainage line is drawn in on location maps with a black or blue pen. At the ends, AL and the commanded time of exceeding are added.
The flow line is therefore both a spatial and a temporal arrangement. Without a sequence line, all units involved in the attack would have to be given separate orders as to where and when to attack.
- Army Service Regulations (HDv) 100/100 leadership in combat