Remarks 

The $P directive is meaningful only for code compiled in the {$H-} state, and is provided for backwards compatibility with early versions of Delphi and CodeGear Pascal. $P controls the meaning of variable parameters declared using the string keyword in the {$H-} state. In the {$P-} state, variable parameters declared using the string keyword are normal variable parameters, but in the {$P+} state, they are open string parameters. Regardless of the setting of the $P directive, the openstring identifier can always be used to declare open string parameters.