code: private function setFirephpHeader($meta, $value = null)
      {
          $msg = \json_encode(array(
              $meta,
              $value,
          ));
          $structureIndex = 1;    // refers to X-Wf-1-Structure-1
          $parts = \explode("\n", \rtrim(\chunk_split($msg, 5000, "\n")));
          $numParts = \count($parts);
          for ($i=0; $i<$numParts; $i++) {
              $part = $parts[$i];
              $this->messageIndex++;
              $headerName = 'X-Wf-1-'.$structureIndex.'-1-'.$this->messageIndex;
              $headerValue = ( $i==0 ? \strlen($msg) : '')
                  . '|' . $part . '|'
                  . ( $i<$numParts-1 ? '\\' : '' );
              $this->outputEvent['headers'][] = array($headerName, $headerValue);
          }
      }
docs: set FirePHP log entry header(s)
  
  @param array $meta  meta information
  @param mixed $value value
  
  @return void