« MODx Parse Error »

MODx encountered the following error while attempting to parse the requested resource:
« PHP Parse Error »
PHP error debug
  Error: Use of undefined constant IN_MANAGER_MODE - assumed 'IN_MANAGER_MODE' (this will throw an Error in a future version of PHP) 
  Error type/ Nr.: Warning - 2 
  File: /virtual/yamakei/public_html/journal/manager/includes/document.parser.class.inc.php 
  Line: 1718 
  Line 1718 source: if(IN_MANAGER_MODE=='true'){  
Parser timing
  MySQL: 0.0000 s s(0 Requests)
  PHP: 0.0012 s s 
  Total: 0.0012 s s