diff --git a/doc/src/sgml/typeconv.sgml b/doc/src/sgml/typeconv.sgml
index f233e9d712e0d2aac157a95efaa869a5704575c2..cca45eb56987546d1f882f5107a5f256e86b109e 100644
--- a/doc/src/sgml/typeconv.sgml
+++ b/doc/src/sgml/typeconv.sgml
@@ -758,9 +758,11 @@ cast is a cast from that type to itself.  If one is found in the
 <structname>pg_cast</> catalog, apply it to the expression before storing
 into the destination column.  The implementation function for such a cast
 always takes an extra parameter of type <type>integer</type>, which receives
-the destination column's declared length (actually, its
-<structfield>atttypmod</> value; the interpretation of
-<structfield>atttypmod</> varies for different data types).  The cast function
+the destination column's <structfield>atttypmod</> value (typically its
+declared length, although the interpretation of <structfield>atttypmod</>
+varies for different data types), and it may take a third <type>boolean</>
+parameter that says whether the cast is explicit or implicit.  The cast
+function
 is responsible for applying any length-dependent semantics such as size
 checking or truncation.
 </para>
@@ -772,17 +774,17 @@ checking or truncation.
 <title><type>character</type> Storage Type Conversion</title>
 
 <para>
-For a target column declared as <type>character(20)</type> the following statement
-ensures that the stored value is sized correctly:
+For a target column declared as <type>character(20)</type> the following
+statement shows that the stored value is sized correctly:
 
 <screen>
 CREATE TABLE vv (v character(20));
 INSERT INTO vv SELECT 'abc' || 'def';
-SELECT v, length(v) FROM vv;
+SELECT v, octet_length(v) FROM vv;
 
-          v           | length
-----------------------+--------
- abcdef               |     20
+          v           | octet_length
+----------------------+--------------
+ abcdef               |           20
 (1 row)
 </screen>
 </para>
@@ -796,7 +798,7 @@ char</>, the internal name of the <type>character</type> data type) to match the
 column type.  (Since the conversion from <type>text</type> to
 <type>bpchar</type> is binary-coercible, this conversion does
 not insert any real function call.)  Finally, the sizing function
-<literal>bpchar(bpchar, integer)</literal> is found in the system catalog
+<literal>bpchar(bpchar, integer, boolean)</> is found in the system catalog
 and applied to the operator's result and the stored column length.  This
 type-specific function performs the required length check and addition of
 padding spaces.