You have assigned a material to a network activity and want to determine the requirement...

To determine the requirement date for a material component assigned to a network activity, you have to maintain the basic dates of the network activity. The basic dates are the earliest possible start and finish dates of an activity or a network, based on its dependencies and constraints. The requirement date for a material component is derived from the basic start date of the activity to which it is assigned. Reference:https://help.sap.com/doc/0f069b2e08b748f1b480d4c8b46c3c49/100/en-US/6a7a9f0a6e421014e10000000a174cb4.html