* File name:
  I_[survey][site][field number]_[filter].[extension]
  -- [survey]      : name of survey
  -- [site]        : for KMTNet case, "C", "S", and "A" indicates "CTIO", "SAO", and "SSO" site, respectively
  -- [field number]: KMTNet field number
  -- [filter]      : filter used for observations
  -- [extension]   : explained below

* File extension:
  -- [TLC]: tender-loving-care (TLC) reductions of the light curve observed at each KMTNet observatory for modeling 
  -- [dia]: differential image analysis (pyDIA) reductions for measuring the source color, using an identical magnitude scale to KMT CMD
  -- [cmd]: Color-magnitude diagrams (CMD) of KMTNet and OGLE-III

* File formats:
  # =========================================================
  # For KMTNet [TLC] [dia],
  # =========================================================
  # column        value                      unit 
  # ---------------------------------------------------------
      1     HJD' = HJD -245000.0       days
      2     Magnitude in I or V filter instrumental magnitude
      3     Magnitude error            instrumental magnitude
      4     seeing                     arcsecond
      5     background level           ADU
  # =========================================================

  # =========================================================
  # For KMTNet CMD [cmd],
  # =========================================================
  # column        value                      unit 
  # ---------------------------------------------------------
      1     star ID                    ---
      2     x position                 pixel
      3     y position                 pixel
      4     V-band magnitudes          instrumental magnitude
      5     V-band magnitude error     instrumental magnitude
      6     I-band magnitudes          instrumental magnitude
      7     I-band magnitude error     instrumental magnitude
  # =========================================================

