Description
bool 
trigger_error ( string error_msg [, int error_type] )
   Used to trigger a user error condition, it can be used by in conjunction
   with the built-in error handler, or with a user defined function that has
   been set as the new error handler
   (set_error_handler()). 
  
   This function is useful when you need to generate a particular response to
   an exception at runtime.