To specify multiple tags you need to use an array ref:

my $tags = [ "arc", "tall" ];
...
$widget->configure(-tags => $tags);
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Also, see the example in the perlTk documentation Canvases and tags.

In this example, $tags is a scalar, so you can pass it to a subroutine like you would pass a string:

$tags = [ "arc", "tall" ];
build_widget($frame, $tags);
...
sub build_widget {
  my ($frame, $tags) = @_;
  ...
  $widget->configure(-tags => $tags);
}
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