Use the Surfer 6 Text Grid format to add information to the bottom of the grid (GRD) file.  Surfer does not use any information after the last Z value in the GRD file. 

One use for this procedure is to add a text version of the gridding report to the end of the file (e.g. the data file and columns used, any data filtering specified, the gridding method and parameters, etc). Surfer does not read this information, but you can view the information at any time in a text editor.

GRD Surfer 6 Text Grid

  DSAA
  nCols nRows
  xMin xMax
  yMin yMax
  zMin zMax
  z11 z21 z31 ...
  ... znCols znRows
  <additional text or data>

 For more information on the Surfer 6 Text Grid file format, please see here.

Updated November, 2021