I found the following use of : in a module. I have scanned the perl docs I thought relevant (tie and module), but cant find what it means. Can anyone point me to an explanation of what is happening?

The specific line is my $value: Value = 0;

I know that Value is a package below XUL::Node::MVC but what I cant figure out is what '$value:' is doing, or is it ': Value'? Is this a tie? Is it a shortcut for Value->new? The context is in an example (XUL/Node/Application/MultipleViewsExample.pm) in XUL::Node viz.,

use strict;
use warnings;
use Carp;
use XUL::Node::MVC;

use base 'XUL::Node::Application';

sub start {
        my $value: Value = 0; # <--- I dont understand this line
        Window(SIZE_TO_CONTENT,
                VBox(
                        HBox(
                                Button(label => '+', Click => sub { $v
+alue++ }),
                                Button(label => '-', Click => sub { $v
+alue-- }),
                        ),
                        Label(value => $value),
                        TextBox(DISABLED, value => $value),
                ),
        );

return tied($value); # DO NOT REMOVE!- this is for unit testing MVC
                     # and for unit tests only. Lets us check the valu
+e
                     # from the outside
}

1;
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