--- a/README.rst	Wed Dec 21 23:04:25 2011 +0200
+++ b/README.rst	Wed Dec 21 23:16:32 2011 +0200
@@ -29,6 +29,27 @@
 Dictionary source file format.
 ==============================
 
+For source file format used dictd C5 file format. See::
+
+  $ man 1 dictfmt
+
+Shortly:
+
+ * Headwords preceded by 5 or more underscore characters ``_`` and a
+   blank line.
+ * All text until the next headword is considered the definition.
+ * Any leading ``@`` characters are stripped out, but the file is
+   otherwise unchanged.
+
+For convenience also used such assumptions:
+
+ * Headwords separated by ``;<SPACE>`` (and all was placed on single
+   line).
+ * UTF-8 encoding was used.
+ * Lines started with ``#`` striped out (comment syntax).
+ * First line with ``ABOUT:`` used as description of dictionary.
+ * First URL (line with ``http://``) used as dictionary home page.
+
 IPA chars.
 ==========