{ # Expand tag names into referenced name sets
    my %seen;    
    $EXPORT_TAGS{all} = [ 
            grep { !$seen{$_}++ } 
            map { m/^:(.*)$/ ? @{$EXPORT_TAGS{$1}} : $_ } 
            @{$EXPORT_TAGS{all}} 
        ];
    }

    { # Add tag set names not already listed into @EXPORT_OK
    my %seen;    
    $seen{$_}++ foreach @EXPORT_OK;
    push @EXPORT_OK,
        grep { !$seen{$_}++ } 
        @{$EXPORT_TAGS{$_}} foreach keys %EXPORT_TAGS;
    }