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+This directory contains examples for the 'chem' language.
+
+You can view the graphical display of the examples by calling
+
+    @g@chem <file> | groff -p ...
+
+On the displays, you can see rings consisting of several lines and
+bonds (lines).  All points on rings and bonds that do not have a
+notation mean a C atom (carbon) filled with H atoms (hydrogen) such
+that the valence of 4 is satisfied.
+
+For example, suppose you have just a single line without any
+characters.  That means a bond.  It has two points, one at each end of
+the line.  So each of these points stands for a C atom, the bond
+itself connects these 2 C atoms.  To fulfill the valence of 4, each
+points has to carry additionally 3 H atoms.  So the single empty bond
+stands for CH3-CH3, though this combination doesn't make much sense
+chemically.
+
+
+####### License
+
+Copyright (C) 2006-2020 Free Software Foundation, Inc.
+Written by Bernd Warken <groff-bernd.warken-72@web.de>.
+
+This file is part of 'chem', which is part of 'groff'.
+
+'groff' 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.
+
+'groff' 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.
+
+The GPL2 license text is available in the internet at
+<http://www.gnu.org/licenses/gpl-2.0.html>.
+
+
+##### Editor settings
+Local Variables:
+fill-column: 72
+mode: text
+End:
+vim: set textwidth=72: