Digital Nautical Chart (DNC) - NGA

MIL-PRF-89023
their pathnames (DNC03\GEN03\MKNN is a 3° tile in the GENERAL library and
DNC03\COA03\MKNN is a 3° tile in the COASTAL library of the DNC03 database).
TABLE 2. DNC tile sizes.
LIBRARY
(Chart Type)
TILE SIZE CHART SCALES
GENERAL 3º 1:50,000
b. GEOREF description. There are 24 longitudinal zones each of 15
degrees width extending eastward from the 180º meridian around the globe
through 360 degrees of longitude. These zones are lettered from A to Z
inclusive (omitting I and O). There are 12 bands of latitude each of 15
degrees height, extending northward from the South Pole. These bands are
lettered from A to M inclusive (omitting I) northward from the South Pole.
This code divides the earth's surface into 288 15-degree quadrangles, each of
which is identified by two letters. The first letter is that of the longitude
zone and the second letter that of the latitude band. Each 15-degree
quadrangle is sub-divided into 15 one-degree bands of longitude eastward from
the western meridian of the quadrangle. These one-degree units are lettered
from A to Q inclusive (omitting I and O). Each 15-degree quadrangle is also
sub-divided into 15 one-degree bands of latitude northward from the southern
parallel of the quadrangle. These bands are lettered from A to Q inclusive
(omitting I and O). See FIGURE 1.
K
Q
P
N
M
L
K
J
H
G
F
E
D
C
B
A
1° x 1° TILE MKNQ
A B C D E F G H J K L M N P Q
M
GEOREF 15° x 15° OFFSET = MK 15° W.
Longitude, 45° N. Latitude
6
15° x 15°
FIGURE 1. 1º by 1º GEOREF tiling scheme example.
For the GENERAL and COASTAL libraries, each 15-degree quadrangle is subdivided
into five three-degree bands of longitude eastward from the western
meridian, and five three-degree bands of latitude northward from the southern