c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my $line = qq{foo\t bar\t\tbaz\t\nboff};
 print qq{>>$line<<};
 dd $line;
 ;;
 my @fields = split '\t\s', $line;
 dd \@fields;
"
>>foo    bar            baz
boff<<
"foo\t bar\t\tbaz\t\nboff"

["foo", "bar", "baz", "boff"]

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my $line = qq{foo\t bar\t\tbaz\t\nboff};
 print qq{>>$line<<};
 dd $line;
 ;;
 my @fields = split qq{\t\s}, $line;
 dd \@fields;
"
Unrecognized escape \s passed through at -e line 1.
>>foo    bar            baz
boff<<
"foo\t bar\t\tbaz\t\nboff"

["foo\t bar\t\tbaz\t\nboff"]