Well, our can be used in the way you mention. It can also be used very much like use vars is used. However, using our like use vars is a bad idea (see Why is 'our' good?).

So, if I wasn't worried about supporting pre-5.6 Perl, I might write code like:

use strict;
package A;
{
    our %OPT= (
        fred => 1,
        barney => 2,
    );
}
sub getopts {
    our %OPT;
    # ...
}
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but probably only if %OPT needed to be global, that is accessible outside the scope of this file. Otherwise I'd just use:

my %OPT= ( ... );
sub getopts {
    # Global( =%OPT );
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        - tye (but my friends call me "Tye")