format
The format is:
Formal class 'SpatialGridDataFrame' [package "sp"] with 6 slots
..@ data :'data.frame': 259200 obs. of 1 variable:
.. ..$ pa2000.asc: num [1:259200] NA NA NA NA NA NA NA NA NA NA ...
..@ grid :Formal class 'GridTopology' [package "sp"] with 3 slots
.. .. ..@ cellcentre.offset: num [1:2] -179.8 -89.8
.. .. ..@ cellsize : num [1:2] 0.5 0.5
.. .. ..@ cells.dim : int [1:2] 720 360
..@ grid.index : int(0)
..@ coords : num [1:2, 1:2] -179.8 179.8 -89.8 89.8
.. ..- attr(*, "dimnames")=List of 2
.. .. ..$ : NULL
.. .. ..$ : chr [1:2] "coords.x1" "coords.x2"
..@ bbox : num [1:2, 1:2] -180 -90 180 90
.. ..- attr(*, "dimnames")=List of 2
.. .. ..$ : chr [1:2] "coords.x1" "coords.x2"
.. .. ..$ : chr [1:2] "min" "max"
..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots
.. .. ..@ projargs: chr " +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0"source
http://www.iiasa.ac.at/web-apps/ggi/GgiDb/dsd?Action=htmlpage&page=about