What made you want to look up negative valence? Please tell us where you read or heard it (including the quote, if possible).
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.
HASS was designed for those with sprinkler knowledge and capable of making value judgments concerning the calculations. The operator is responsible for proper use of HASS as a tool in completing a given design or layout. You will want to spend some time with HASS using sample data and various options before you begin serious use.