When in the system event cycle are [(site_start)], [(site_url)], etc. parsed?

    function executeParser() {
        //error_reporting(0);
        if (version_compare(phpversion(), "5.0.0", ">="))
            set_error_handler(array (
                & $this,
                "phpError"
            ), E_ALL);
        else
            set_error_handler(array (
                & $this,
                "phpError"
            ));

        $this->db->connect();

        // get the settings
        if (empty ($this->config)) {
            $this->getSettings();
        }

// combine template and document variables
$source= $this->mergeDocumentContent($source);
// replace settings referenced in document
$source= $this->mergeSettingsContent($source);
// replace HTMLSnippets in document
$source= $this->mergeChunkContent($source);
// insert META tags & keywords
$source= $this->mergeDocumentMETATags($source);
// find and merge snippets
$source= $this->evalSnippets($source);
// find and replace Placeholders (must be parsed last) - Added by Raymond
$source= $this->mergePlaceholderContent($source);

      // Do automatic conversion of quoted URLs
      $content
        = preg_replace(
          '/"('
            . '\[\(site_url\)\]'
            . '|\[\(base_url\)\]'
            . '|' . preg_quote( $this->itsMODx->config['site_url'], '/' )
            . '|' . preg_quote( $this->itsMODx->config['base_url'], '/' )
            . '|'
            . ')'
            . '\[~(.*)~\]"/U'
            . $this->itsEncodingModifier
          , '"(yams_docr:\2)"'
          , $content
          , -1
        );