#!/usr/bin/perl
use strict;
use warnings;

while(<DATA>) {
	if( m{  \A  OBX  \|  [^|]*  \|  }gmsx ) {
		s{
			\G (?: ([[:upper:]]) | ([[:lower:]]) | ([^\^]) )
		}{
			defined $1 ? "U$1" :
			defined $2 ? "L$2" :
			$3
		}sexmg;
	}
	print;
}

__END__
NTE||L|obr note
OBX|NM|aaA..^Haem^RD2|7.5|g/dL|13.0-18.0|OR|
NTE||L|obx note 1/1 for 3058
OBX|NM|dBf..^TWC^RD2|8.9|10*9/L|4.0-11.0||