The weightage amount or percentage value drives the service allocation for the customer. For example, you can set 60:40 service allocation amongst two service products depending upon service implementation needs.
If your administrator has set the global flag isTriggerInitiatedUpdate to True, CPQ skips the trigger logic, which allocates the net price of the service line item to all associated related line item records based on the Weightage Type and Weightage Amount fields. For more information, see Configuring the Execution of the RelatedLineItem Trigger.