new file mode 100644
--- /dev/null
+++ b/scripts/control/is_signal_list.m
@@ -0,0 +1,33 @@
+# Copyright (C) 1996,1998 A. Scottedward Hodel
+#
+# This file is part of Octave.
+#
+# Octave 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 2, or (at your option) any
+# later version.
+#
+# Octave 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 Octave; see the file COPYING.  If not, write to the Free
+# Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+function flg = is_signal_list(mylist)
+# function flg = is_signal_list(mylist)
+# returns true if mylist is a list of individual strings.
+# 
+
+flg = is_list(mylist);
+if(flg)
+  for ii=1:length(mylist)
+    if(!(isstr(nth(mylist,ii)) & rows(nth(mylist,ii)) ==1) )
+      flg = 0;
+    endif
+  endfor
+endif
+
+endfunction