Function GED_L3_CORR - get ERNE Correction Factors for Level-3 Data.
                        TM-formats: f10,f30,f40,f50

 Version 2.0


 Calling sequence:

	data=GED_L3_CORR()


 Input parameters:

        none




 Returns:

        Level 3 ERNE Correction Factors read from disk file is returned as an array of structures (see below).




 Keyword parameters:

	filename  fn
                  A string containing the name of the disk file to be read. If set to an
                  empty named variable, DIALOG_PICKFILE is invoked to select the file
                  interactively and the variable is used for returning the selection.
                  DIALOG_PICKFILE is invoked also if 'filename' is missing.
                  If DIALOG_PICKFILE is invoked, the name of the selected file will also
                  be printed to standard output.


	G3COR_FP  path
                  A string containing the directory where to look for files. If set to named
                  variable, the directory of the specified or selected file is returned.


	G3COR_PAR params
                  If set to a named variable, a structure of (auxiliarity) parameter data
                  present in the correction factor file will be returned in the variable.
                  See also keyword 'GED_1ST' below.


	GED_1ST   firstcall
                  If 'firstcall' is set, the 'params' variable will return just the
                  parameters for the current file. Otherwise, and providing variable 'params'
                  is set on entry, it is assumed that the variable contains (an array of)
                  earlier parameter value(s) and the current record will be added at the end
                  of that. This is mainly intended for internal use of the 'GED'-system, but
                  it is allright to use in direct calls also when user wants to clear the
                  earlier contents of the variable.




 Version history:


 2.0
       2007-01-17 (ER)

       Updated to utilize automated (on-need) structure definition.


 1.0

	2004-12-10 (ER)

       Original version based on 'red_l3f10_corr.pro'.