sub parse_lab_test {
    @segs = split('\r', $b);  # \r is the record terminator
    foreach $seg (@segs) {
        $segtype = substr($seg, 0, 3);
        if ($segtype eq "MSH") {
           msh_fields($seg);
        } elsif ($segtype eq "PID") {
           pid_fields($seg);
        } elsif ($segtype eq "PV1") {
           pv1_fields($seg);

		  ... etc ...

	} else {
           &segment_error;
        } 
    }
}