Adjust ( $Date, $DeltaYears, $DeltaMonths, $DeltaDays );

##</code><code>##

Adjust ( $Date, 0, 0, 15 );  # or
Adjust ( $Date, 0, -1, 0 );  # or
Adjust ( $Date, -3, 0, -1 );

##</code><code>##

Adjust ( { date => $Date, day => 15 } );  # or
Adjust ( { date => $Date, month => -1 } );  # or
Adjust ( { date => $Date, year => -3, day => -1 } );

##</code><code>##

sub Adjust
{
  my ( $Args ) = @_;

  my $Year  = $Args->{ year }  || 0;
  my $Month = $Args->{ month } || 0;
  my $Day   = $Args->{ day }   || 0;

  #  More code ..
}