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WBS is nothing but Work Breakdown Structure. It is mainly used in Project System (PS) module. Tcode: CJ20N. For any project defined we must have atleast one WBS. Within this WBS we can have networks. Networks are nothing but the series of activities. Material are used to perform the activities.
In this capacity, the WBS is a key project process deliverable, used to facilitate project planning and the related scheduling of all tasks and activities. There is no singular approach to WBS preparation, nor is there one format to follow.