These naming conventions are standard for model distributions involving specific costumes or "R15" physical physics.
Are you trying to this model into a specific game or customize its appearance?
These tags are common on platforms like Booth.pm or Gumroad, where creators sell or share 3D models with specific "EX" (expression/outfit) toggles.
Often denotes a "Version 2" or an "Expansion" of an existing model or asset pack.