The Federal Railroad Administration sponsored Transportation Technology Center, Inc., (MxV Rail), in collaboration with a rail industry stakeholder technical advisory group (TAG), to refine concepts and develop interoperable requirements for the Full Moving Block (FMB) method of train control. The team worked to develop an FMB Concept of Operations (ConOps) document with a focus on interfacing with alternative broken rail and rollout detection (ABRRD) system architectures; develop an Incremental FMB System and Segment Requirements Specification document; develop ABRRD system requirements; redline the Interoperable Train Control (ITC) Office-Locomotive Segment Interface Control Document (ICD), as well as the ITC Wayside-Locomotive Segment ICD, to capture recommended changes; develop migration considerations; and conduct a preliminary safety analysis. Research was conducted from May 2020 to September 2022.