Noted by Daniele Varrazzo.
</listitem>
</varlistentry>
+ <varlistentry>
+ <term><replaceable class="parameter">left_type</replaceable></term>
+ <term><replaceable class="parameter">right_type</replaceable></term>
+ <listitem>
+ <para>
+ The data type(s) of the operator's arguments (optionally
+ schema-qualified). Write <literal>NONE</> for the missing argument
+ of a prefix or postfix operator.
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry>
<term><literal>PROCEDURAL</literal></term>