That is most strange. Do not know about Singapore, but many countries only publish OCH/A in their AIPs derived from obstacle survey and procedure design. I just checked AIP U.K. and yes is shows OCH of about 160 ft for CAT I ILS. It is no nosense, that is your obstacle floor. We all know that minima for CAT I ILS are no less than 200 feet. So no problem. Only that the pilot - operator must take data from AIP and create minima out of them observing all applicable regulations normally from Annex 6 / JAR OPS / applicable FAR part. One way to do it is to buy AREAD / Jepp an use this. Of course, should you make an error due to wrongly printed book it is entirely your fault.
machlimiter99: Many would argue that is it only perfect way to do it. However some commercial publications are more user friendly and make very sure you well understand the difference between OCA/H vs. DA/H & MDA/H as described above.
Fd
(the un-real)