+ my $compare = (
+ !defined $ver ? undef : # last column if nameless
+ ref $data ne 'HASH' ? '' : # unclassified if no support hash
+ $data->{ $ver->[-1] } // $prev # known or inherit from predecessor
+ // (grep { defined } @{$data}{ map { $_->[0] } @{ $versions{$browser} } })[0]
+ ~~ 'n' && 'n' # first known version is unsupported
+ || 'u' # unsure
+ );
+ unless (!defined $prev or $prev ~~ $compare) {
+ my @vercover = (map { @{$_} } @span);
+ for ($ver ? @{$ver} : ()) {
+ $data->{$_} eq $data->{$vercover[-1]} or last;
+ push @vercover, $_; # matches from next span start
+ }
+ my $usage = sum(@{ $canihas->{$browser} }{@vercover});
+
+ # strip #\d note references from support class
+ my @notes;
+ push @notes, $feature->{notes_by_num}->{$1}
+ while $prev =~ s/\h \# (\d+) \b//x;
+
+ # prepare version hover details
+ my $title = sprintf('%.1f%% %s', $usage * $usagepct, join(' ',
+ (map { ref $_ eq 'CODE' ? $_->($browser, $vercover[0]) : $_ }
+ map { $DSTATS{$_} // () }
+ map { split / /, $_ }
+ $prev
+ ),
+ 'in', $caniuse->{agents}->{$browser}->{abbr},
+ showversions(@vercover, undef),
+ ));
+ $title .= "\n$_" for notestotitle(@notes);
+
+ printf('<td class="%s" colspan="%d" title="%s">%s',