Like the Army, while experience gained as an XO is highly beneficial for an Air Force officer's professional development, it is not necessarily a prerequisite for a command position. However, it is often the norm that nearly all Air Force commanders will have been an XO at some point earlier in their careers. For officers holding second-in-command positions, the U.S. Air Force uses the titles of "vice commander" (CV), or "deputy commander" (CD) for an officer who serves as the second-in-command for an organization above squadron level. For a squadron level organization, the second-in-command is typically termed the "director of operations" or "operations officer" (DO). These latter terms were previously used for similar positions at the group and wing level until renamed as the "operations group commander (OG/CC). The rank of an executive officer in the U.S. Air Force can vary from a junior officer supporting a mid level commander up to a senior field grade (FGO) supporting a general officer.