Which of the following is NOT a material type used in GFEBS?

The classification of materials in systems like GFEBS (General Fund Enterprise Business System) is critical for proper financial management and inventory control. In this context, "Fixed Assets" refers to long-term tangible assets that are not typically classified as inventory for operational purposes. Fixed assets include things like buildings, machinery, and equipment that have a long-term use and are not directly consumed in operations.

The other options represent classifications that are more aligned with inventory and supply management. "Operating Supplies" are items that are used in the day-to-day operations of an organization but are not necessarily kept in stock. "Non-Stock Materials" refer to items that are identified for one-time use or that do not need to be stocked. "Service" often pertains to non-material items or contracts for services rendered, which are also categorized differently from traditional material types.

Thus, "Fixed Assets" stands out as it does not fit within the conventional material types used in supply chain and inventory management, making it the correct answer as not being classified as a material type in GFEBS.