</warning>
      </listitem>
     </varlistentry>

     <varlistentry id="libpq-connect-oauth-client-id" xreflabel="oauth_client_id">
      <term><literal>oauth_client_id</literal></term>
      <listitem>
       <para>
        An OAuth 2.0 client identifier, as issued by the authorization server.
        If the <productname>PostgreSQL</productname> server
        <link linkend="auth-oauth">requests an OAuth token</link> for the
        connection (and if no <link linkend="libpq-oauth-authdata-hooks">custom
        OAuth hook</link> is installed to provide one), then this parameter must
        be set; otherwise, the connection will fail.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="libpq-connect-oauth-client-secret" xreflabel="oauth_client_secret">
      <term><literal>oauth_client_secret</literal></term>
      <listitem>
       <para>
        The client password, if any, to use when contacting the OAuth
        authorization server. Whether this parameter is required or not is
        determined by the OAuth provider; "public" clients generally do not use
        a secret, whereas "confidential" clients generally do.
       </para>
      </listitem>
     </varlistentry>

     <varlistentry id="libpq-connect-oauth-scope" xreflabel="oauth_scope">
      <term><literal>oauth_scope</literal></term>
      <listitem>
       <para>
        The scope of the access request sent to the authorization server,
        specified as a (possibly empty) space-separated list of OAuth scope
        identifiers. This parameter is optional and intended for advanced usage.
       </para>
       <para>
        Usually the client will obtain appropriate scope settings from the
        <productname>PostgreSQL</productname> server. If this parameter is used,
        the server's requested scope list will be ignored. This can prevent a
        less-trusted server from requesting inappropriate access scopes from the
        end user. However, if the client's scope setting does not contain the
        server's required scopes, the server is likely to reject the issued
        token, and the connection will fail.
       </para>
       <para>
        The meaning of an empty scope list is provider-dependent. An OAuth
        authorization server may choose to issue a token with "default scope",
        whatever that happens to be, or it may reject the token request
        entirely.
       </para>
      </listitem>
     </varlistentry>

    </variablelist>
   </para>
  </sect2>
 </sect1>

 <sect1 id="libpq-status">
  <title>Connection Status Functions</title>

  <para>
   These functions can be used to interrogate the status
   of an existing database connection object.
  </para>

  <tip>
   <para>
    <indexterm><primary>libpq-fe.h</primary></indexterm>
    <indexterm><primary>libpq-int.h</primary></indexterm>
    <application>libpq</application> application programmers should be careful to
    maintain the <structname>PGconn</structname> abstraction.  Use the accessor
    functions described below to get at the contents of <structname>PGconn</structname>.
    Reference to internal <structname>PGconn</structname> fields using
    <filename>libpq-int.h</filename> is not recommended because they are subject to change
    in the future.
   </para>
  </tip>

  <para>
   The following functions return parameter values established at connection.
   These values are fixed for the life of the connection.  If a multi-host
   connection string is used, the values of <xref linkend="libpq-PQhost"/>,
   <xref linkend="libpq-PQport"/>, and <xref linkend="libpq-PQpass"/> can change if a new connection
   is established using the same <structname>PGconn</structname> object.  Other values
   are fixed for the lifetime of the <structname>PGconn</structname> object.

   <variablelist>
    <varlistentry id="libpq-PQdb">
     <term><function>PQdb</function><indexterm><primary>PQdb</primary></indexterm></term>

     <listitem>
      <para>