Method of Demarcation for Grid Square

The main Grid Square Statistics compiled by the government institutions including the Statistics Bureau of the Ministry of Internal Affairs and Communications are based on Announcement No.143, using the Standard Grid Square.

In this announcement, the Standard Grid Square is divided into three categories: Basic Grid Square, Divided Grid Square and Integrated Grid Square, describing the method of demarcation for each Grid Square and the definition of each code.

The method of demarcation for the Standard Grid Square is as follows:
A Primary Area Partition is demarcated by 40 minutes of latitude and 1 degree of longitude. The Secondary Area Partition is demarcated by dividing a Primary Area Partition into 64 (8 by 8) equal parts vertically and horizontally, and the Basic Grid Square (Third Area Partition) is demarcated by dividing a Secondary Area Partition into 100 (10 by 10) equal parts vertically and horizontally.

Chart

Partition	Method of demarcation	Interval of latitude	Interval of longitude	Length of side	Relation with map
Primary Area Partition	Divide the country into some equal parts measuring 2/3 degree of latitude by 1 degree of longitude.	40 minutes	1 degree	about 80 km	One page of 1/200,000 chorography (published by the Geographical Survey Institute)
Secondary Area Partition	Divide a Primary Area Partition into 64 (8 by 8) equal parts towards longitude and latitude.	5 minutes	7 minutes 30 seconds	about 10 km	One page of 1/25,000 topography (published by the Geographical Survey Institute)
Basic Grid Square (Third Area Partition)	Divide a Secondary Area Partition into 100 (10 by 10) equal parts towards longitude and latitude.	30 seconds	45 seconds	about 1 km
Half Grid Square	Dividie a Basic Grid Square (Third Area Partition) into 4 (2 by 2) equal parts towards longitude and latitude.	15 seconds	22.5 seconds	about 500 m