In NetSuite, an item is listed in Demand Planning only if the Replenishment method is set as Time-Phased in the Item Record because this method provides the necessary time-based framework for inventory replenishment.
Time-Phased Replenishment calculates when and how much inventory needs to be ordered based on future demand forecasts over specific time periods (e.g., weekly or monthly). Without this method, NetSuite doesn’t have the required structure to align inventory levels with forecasted demand, making the item ineligible for demand planning. Essentially, Time-Phased Replenishment ensures that inventory is replenished based on forecasted demand over time, which is central to effective demand planning.