--- /dev/null
+## Copyright (C) 2010 Lukas F. Reichlin
+##
+## This program is free software: you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation, either version 3 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {[@var{props}, @var{vals}] =} __property_names__ (@var{sys})
+## @deftypefnx {Function File} {[@var{props}, @var{vals}] =} __property_names__ (@var{sys}, @var{"specific"})
+## Return the list of properties as well as the assignable values for a frd object sys.
+## @end deftypefn
+
+## Author: Lukas Reichlin <lukas.reichlin@gmail.com>
+## Created: October 2010
+## Version: 0.1
+
+function [props, vals] = __property_names__ (sys, flg)
+
+ ## cell vector of tf-specific properties
+ props = {"H";
+ "w"};
+
+ ## cell vector of frd-specific assignable values
+ vals = {"p-by-m-by-l array of complex frequency responses";
+ "l-by-1 vector of real frequencies (l = length (w))"};
+
+ if (nargin == 1)
+ [ltiprops, ltivals] = __property_names__ (sys.lti);
+
+ props = [props;
+ ltiprops];
+
+ vals = [vals;
+ ltivals];
+ endif
+
+endfunction
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