To report errors from an internal function, you should call the
   php3_error() function. This takes at least two
   parameters -- the first is the level of the error, the second is
   the format string for the error message (as in a standard
   printf() call), and any following arguments
   are the parameters for the format string. The error levels are:
  
    Notices are not printed by default, and indicate that the script
    encountered something that could indicate an error, but could also
    happen in the normal course of running a script. For example,
    trying to access the value of a variable which has not been set,
    or calling stat() on a file that doesn't exist.
   
    Warnings are printed by default, but do not interrupt script
    execution.  These indicate a problem that should have been trapped
    by the script before the call was made. For example, calling 
    ereg() with an invalid regular expression.
   
    Errors are also printed by default, and execution of the script is
    halted after the function returns. These indicate errors that can
    not be recovered from, such as a memory allocation problem.
   
    Parse errors should only be generated by the parser. The code is
    listed here only for the sake of completeness.
   
    This is like an E_ERROR, except it is generated by the core
    of PHP. Functions should not generate this type of error.
   
    This is like an E_WARNING, except it is generated by the core
    of PHP. Functions should not generate this type of error.
   
     This is like an E_ERROR, except it is generated by the Zend Scripting
     Engine. Functions should not generate this type of error.
   
     This is like an E_WARNING, except it is generated by the Zend Scripting
     Engine. Functions should not generate this type of error.
   
     This is like an E_ERROR, except it is generated in PHP code by using
     the PHP function trigger_error(). Functions should 
     not generate this type of error.
   
     This is like an E_WARNING, except it is generated  by using the PHP 
     function trigger_error(). Functions should not 
     generate this type of error.
   
     This is like an E_NOTICE, except it is generated by using the PHP
     function trigger_error(). Functions should not 
     generate this type of error.
   
    All of the above.  Using this error_reporting level will show 
    all error types.