Code table 6 -- Data representation type
from the ECMWF publication "Binary data representation - FM 92 GRIB", May 1992

Code
figure    Meaning

0         Latitude/longitude grid -- equidistant cylindrical or Plate 
          Carree projection
1         Mercator projection
2         Gnomonic projection
3         Lambert conformal, secant or tangent, conic or bi-polar, projection
4         Gaussian latitude/longitude grid
5         Polar stereographic projection
6         Universal Transverse Mercator (UTM) projection
7         Simple polyconlc projection
8         Albers equal-area, secant or tangent, conic or bi-polar, projection
9         Miller's cylindrical projection
10        Rotated latitude/longitude grid
11        Reserved
12        "
13        Oblique Lambert conformal, secant or tangent, conic or bi-polar,
          projection
14        Rotated Gaussian latitude/longitude grid
15        \
.
.          Reserved
.
19        /
20        Stretched latitude/longitude grid
21        \
.          Reserved
23        /
24        Stretched Gausslan latitude/longitude grid
25        \
.
.          Reserved
.
29        /
30        Stretched and rotated latitude/longitude grids
31        \
.          Reserved
33        /
34        Stretched and rotated Gaussian latitude/longitude grids
35        \
.        
.          Reserved
.
49        /

50        Spherical harmonic coefficients
51        \
.
.          Reserved
.
59        /
60        Rotated spherical harmonic coefficients
61        \
.
.          Reserved
.
69        /
70        Stretched spherical harmonics
71        \
.
.          Reserved
. 
79        /
80        Stretched and rotated spherical harmonic coefficients
81        \
.
.          Reserved
.
89        /
90        Space view, perspective or orthographic
91        \
.
.          Reserved
.
254       /