There are a few restrictions on your choice of name:

<itemizedlist>

<listitem>

<para><literal>--</literal> and <literal>/*</literal> cannot appear anywhere in an operator name,

<para>

<literal>--</literal> and <literal>/*</literal> cannot appear anywhere in an operator name,

since they will be taken as the start of a comment.

</para>

</listitem>

</listitem>

<listitem>

<para>

Theuse of<literal>=&gt;</literal>as an operator nameisdeprecated. It may

be disallowed altogether in a future release.

Thesymbol<literal>=&gt;</literal> isreserved by the SQL grammar,

so it cannot be used as an operator name.

</para>

</listitem>

</itemizedlist>