while (<DATA>) {
if (/^(?:[A-Z_]+,?)+(?<!,)$/) {print "good";}
else {print "bad";}
print;
}

##</code><code>##

__DATA__
*
*,*
*.*
ABC
ABC*
*ABC
ABC_TO
ABC_TO,DEF,GHI_JKL,GHI_JK1_TO