With effect from 1 April 2002, the Patent Cooperation Treaty was amended, so that the deadline for both Chapter I and Chapter II national or regional phase entry expire at a minimum of 30 months from priority. For most PCT countries, this change took effect immediately. There were, however, a few for which this change did not take effect and, as of the end of May 2002, there were approximately 20 such countries left. Within Asia, such countries include China, Japan, South Korea and Singapore, the last being the only contracting state within South East Asia where the change is not yet effective. As before, the term for entering the National Phase in Singapore under Chapter I is still 20 months from the earliest priority date (or from filing, if priority is not claimed).
