unless ($line =~ m/([A-Z]\d[A-Z]\s*\d[A-Z]\d)/i) {

##</code><code>##

unless ( $line =~ m/([ABCEGHJ-NPRSTVXY][0-9][ABCEGHJ-NPRSTV-Z]\s*[0-9][ABCEGHJ-NPRSTV-Z][0-9])/i ) {