my @link;
while (<DATA>) {
my @l = m~<a\s[^>]+>([^<>]+)</a>~ig;
next unless 3 == @l;
push @link, grep {$_ =~ /^[RT]\d+$/} @l;
}
print "$_\n" for @link;
_ _ D A T A _ _
<A HREF="/pub/databases/transfac/doc/gene1.html#BS" target="_new">BS</A> -202 -135 <A HREF="/cgi-bin/pub/databases/transfac/getTF.cgi?AC=R00929">R00929</A>; HS$IFNB_14.
<A HREF="/pub/databases/transfac/doc/gene1.html#BS" target="_new">BS</A> -167 -94 <A HREF="/cgi-bin/pub/databases/transfac/getTF.cgi?AC=R00916">R00916</A>; HS$IFNB_01; Binding factors: R2 <A HREF="/cgi-bin/pub/databases/transfac/getTF.cgi?AC=T00712">T00712</A>.
<A HREF="/pub/databases/transfac/doc/gene1.html#BS" target="_new">BS</A> -100 -61 <A HREF="/cgi-bin/pub/databases/transfac/getTF.cgi?AC=R00917">R00917</A>; HS$IFNB_02; Binding factors: IRF1 <A HREF="/cgi-bin/pub/databases/transfac/getTF.cgi?AC=T00422">T00422</A>, IRF-2
<A HREF="/pub/databases/transfac/doc/gene1.html#BS" target="_new">BS</A> <A HREF="/cgi-bin/pub/databases/transfac/getTF.cgi?AC=T00425">T00425</A>.