% Purpose
%    gets variable code list in the data file.
%
% Synopsis
%    var_list = mexeps('varlist')
%
% Description
%    It returns a list of variable codes from the current
%    data file.  Many other mexeps operations require
%    variable code as the input argument when the operation 
%    is related to a variable. A variable in an EPIC System
%    file is refered to by its variable code.
%
% Examples
%    Open a pointer file and get the variable code from 
%    each data file.
%
%      infile = 'eps_to_plot.ptr';            
%      currentfile = mexeps('openr',infile); 
%      while(currentfile ~= ' ')
%	 var_list = mexeps('varlist')
%	  ...
%
%	 currentfile = mexeps('setnextr');
%      end
%      mexeps('close')
%
% See Also
%    varshape, inqvar, getvar, setvar, putvar
%