diff --git a/contrib/unaccent/unaccent.c b/contrib/unaccent/unaccent.c
index a337df61af..5a31f85a13 100644
--- a/contrib/unaccent/unaccent.c
+++ b/contrib/unaccent/unaccent.c
@@ -104,11 +104,21 @@ initTrie(char *filename)
 
 			while ((line = tsearch_readline(&trst)) != NULL)
 			{
-				/*
-				 * The format of each line must be "src trg" where src and trg
-				 * are sequences of one or more non-whitespace characters,
-				 * separated by whitespace.  Whitespace at start or end of
-				 * line is ignored.
+				/*----------
+				 * The format of each line must be "src" or "src trg", where
+				 * src and trg are sequences of one or more non-whitespace
+				 * characters, separated by whitespace.  Whitespace at start
+				 * or end of line is ignored.  If trg is omitted, an empty
+				 * string is used as the replacement.
+				 *
+				 * We use a simple state machine, with states
+				 *	0	initial (before src)
+				 *	1	in src
+				 *	2	in whitespace after src
+				 *	3	in trg
+				 *	4	in whitespace after trg
+				 *	-1	syntax error detected (line will be ignored)
+				 *----------
 				 */
 				int			state;
 				char	   *ptr;
@@ -160,7 +170,14 @@ initTrie(char *filename)
 					}
 				}
 
-				if (state >= 3)
+				if (state == 1 || state == 2)
+				{
+					/* trg was omitted, so use "" */
+					trg = "";
+					trglen = 0;
+				}
+
+				if (state > 0)
 					rootTrie = placeChar(rootTrie,
 										 (unsigned char *) src, srclen,
 										 trg, trglen);
diff --git a/doc/src/sgml/unaccent.sgml b/doc/src/sgml/unaccent.sgml
index af9cad5d8c..aef0031dcb 100644
--- a/doc/src/sgml/unaccent.sgml
+++ b/doc/src/sgml/unaccent.sgml
@@ -45,9 +45,9 @@
   <itemizedlist>
    <listitem>
     <para>
-     Each line represents a pair, consisting of a character with accent
-     followed by a character without accent.  The first is translated into
-     the second.  For example,
+     Each line represents one translation rule, consisting of a character with
+     accent followed by a character without accent.  The first is translated
+     into the second.  For example,
 <programlisting>
 &Agrave;        A
 &Aacute;        A
@@ -57,6 +57,27 @@
 &Aring;        A
 &AElig;        A
 </programlisting>
+     The two characters must be separated by whitespace, and any leading or
+     trailing whitespace on a line is ignored.
+    </para>
+   </listitem>
+
+   <listitem>
+    <para>
+     Alternatively, if only one character is given on a line, instances of
+     that character are deleted; this is useful in languages where accents
+     are represented by separate characters.
+    </para>
+   </listitem>
+
+   <listitem>
+    <para>
+     As with other <productname>PostgreSQL</> text search configuration files,
+     the rules file must be stored in UTF-8 encoding.  The data is
+     automatically translated into the current database's encoding when
+     loaded.  Any lines containing untranslatable characters are silently
+     ignored, so that rules files can contain rules that are not applicable in
+     the current encoding.
     </para>
    </listitem>
   </itemizedlist>
@@ -132,8 +153,8 @@ mydb=# select ts_headline('fr','H&ocirc;tel de la Mer',to_tsquery('fr','Hotels')
 
  <para>
   The <function>unaccent()</> function removes accents (diacritic signs) from
-  a given string.  Basically, it's a wrapper around the
-  <filename>unaccent</> dictionary, but it can be used outside normal
+  a given string.  Basically, it's a wrapper around
+  <filename>unaccent</>-type dictionaries, but it can be used outside normal
   text search contexts.
  </para>
 
@@ -145,6 +166,11 @@ mydb=# select ts_headline('fr','H&ocirc;tel de la Mer',to_tsquery('fr','Hotels')
 unaccent(<optional><replaceable class="PARAMETER">dictionary</replaceable>, </optional> <replaceable class="PARAMETER">string</replaceable>) returns <type>text</type>
 </synopsis>
 
+ <para>
+  If the <replaceable class="PARAMETER">dictionary</replaceable> argument is
+  omitted, <literal>unaccent</> is assumed.
+ </para>
+
  <para>
   For example:
 <programlisting>