SONGetExtMarkInfo

  SONGETEXTMARKINFO returns details about an extended marker channel

  [UNITS, POINTS, PRETRIG]=SONGETEXTMARKINFO(FH, CHAN)

  INPUTS: FH the SON file handle 
          CHAN channel number (0 - SONMaxChans()-1)

  OUTPUTS:   UNITS a string with the channel units
             POINTS the number of items of extra data
             PRETRIG the number of pre-trigger items

  Returns no error codes

  Author:Malcolm Lidierth
  Matlab SON library:
  Copyright © The Author & King's College London 2005-2006