       the installation's <TT
CLASS="LITERAL"
>SHAREDIR</TT
> directory.  The
        default behavior is equivalent to specifying
        <TT
CLASS="LITERAL"
>directory = 'extension'</TT
>.
       </P
></DD
><DT
><TT
CLASS="VARNAME"
>default_version</TT
> (<TT
CLASS="TYPE"
>string</TT
>)</DT
><DD
><P
>        The default version of the extension (the one that will be installed
        if no version is specified in <TT
CLASS="COMMAND"
>CREATE EXTENSION</TT
>).  Although
        this can be omitted, that wil