I need to keep the content of non-HTML tags delimited by "<...>"

Thanks for this awesome module. When indexing an attached PDF (containing no HTML) with an OCR layer, extracted by TIKA, one messy graphic is interpreted to contain "<". About 7 pages later, another messier graphic is interpreted to contain ">". So they, and everything in between were omitted in the index.

Is there a way to include the content of "<...>" when it is NOT a known tag?
I have found other cases where only "<" appears and all that follows is omitted.

I'm not much of a programmer, so am looking for some help here. Thanks for any help/tips you can provide.

I found these three relevant functions, the second of which is called at the end of the first one:

/**
 * Extract HTML tag contents from $text and add to boost fields.
 *
 * @param ApacheSolrDocument $document
 * @param string $text
 *   must be stripped of control characters before hand.
 *
 */
function apachesolr_index_add_tags_to_document(ApacheSolrDocument $document, $text) {
  $tags_to_index = _apachesolr_tags_to_index();

  // Strip off all ignored tags.
  $allowed_tags = '<' . implode('><', array_keys($tags_to_index)) . '>';
  $text = strip_tags($text, $allowed_tags);

  preg_match_all('@<(' . implode('|', array_keys($tags_to_index)) . ')[^>]*>(.*)</\1>@Ui', $text, $matches);
  foreach ($matches[1] as $key => $tag) {
    $tag = drupal_strtolower($tag);
    // We don't want to index links auto-generated by the url filter.
    if ($tag != 'a' || !preg_match('@(?:http://|https://|ftp://|mailto:|smb://|afp://|file://|gopher://|news://|ssl://|sslv2://|sslv3://|tls://|tcp://|udp://|www\.)[a-zA-Z0-9]+@', $matches[2][$key])) {
      if (!isset($document->{$tags_to_index[$tag]})) {
        $document->{$tags_to_index[$tag]} = '';
      }
      $document->{$tags_to_index[$tag]} .= ' ' . apachesolr_clean_text($matches[2][$key]);
    }
  }
}

/**
 * Strip html tags and also control characters that cause Jetty/Solr to fail.
 */
function apachesolr_clean_text($text) {
  // Remove invisible content.
  $text = preg_replace('@<(applet|audio|canvas|command|embed|iframe|map|menu|noembed|noframes|noscript|script|style|svg|video)[^>]*>.*</\1>@siU', ' ', $text);
  // Add spaces before stripping tags to avoid running words together.
  $text = filter_xss(str_replace(array('<', '>'), array(' <', '> '), $text), array());
  // Decode entities and then make safe any < or > characters.
  $text = htmlspecialchars(html_entity_decode($text, ENT_QUOTES, 'UTF-8'), ENT_QUOTES, 'UTF-8');
  // Remove extra spaces.
  $text = preg_replace('/\s+/s', ' ', $text);
  // Remove white spaces around punctuation marks probably added
  // by the safety operations above. This is not a world wide perfect solution,
  // but a rough attempt for at least US and Western Europe.
  // Pc: Connector punctuation
  // Pd: Dash punctuation
  // Pe: Close punctuation
  // Pf: Final punctuation
  // Pi: Initial punctuation
  // Po: Other punctuation, including ¿?¡!,.:;
  // Ps: Open punctuation
  $text = preg_replace('/\s(\p{Pc}|\p{Pd}|\p{Pe}|\p{Pf}|!|\?|,|\.|:|;)/s', '$1', $text);
  $text = preg_replace('/(\p{Ps}|¿|¡)\s/s', '$1', $text);
  return $text;
}

function _apachesolr_tags_to_index() {
  $tags_to_index = variable_get('apachesolr_tags_to_index', array(
    'h1' => 'tags_h1',
    'h2' => 'tags_h2_h3',
    'h3' => 'tags_h2_h3',
    'h4' => 'tags_h4_h5_h6',
    'h5' => 'tags_h4_h5_h6',
    'h6' => 'tags_h4_h5_h6',
    'u' => 'tags_inline',
    'b' => 'tags_inline',
    'i' => 'tags_inline',
    'strong' => 'tags_inline',
    'em' => 'tags_inline',
    'a' => 'tags_a'
  ));
  return $tags_to_index;
}