Possible Clues:

• iOS part: Abbr
• The "S" of GPS, briefly
• The 'S' in CBS or TBS: Abbr
• M.O.: Abbr
• The "S" in iOS: Abbr
• Awacs component: Abbr
• Part of TBS, for short
• CBS segment, for short?
• Extension for Windows driver files
• Method, for short