format
The format is:
Formal class 'SpatialPolygonsDataFrame' [package "sp"] with 5 slots
..@ data :'data.frame': 244 obs. of 51 variables:
.. ..$ ISO3 : Factor w/ 238 levels "-99","AFG","AGO",..: 1 1 1 1 1 1 2 3 4 5 ...
.. ..$ ScaleRank : int [1:244] 5 1 1 1 1 1 1 1 1 1 ...
.. ..$ LabelRank : int [1:244] 5 1 1 1 1 1 1 1 1 1 ...
.. ..$ FeatureCla : Factor w/ 2 levels "Admin-0 countries",..: 1 1 1 1 1 1 1 1 1 1 ...
.. ..$ SOVEREIGNT : Factor w/ 204 levels "Afghanistan",..: 8 80 169 182 137 112 1 4 2 160 ...
.. ..$ SOV_A3 : Factor w/ 205 levels "AFG","AGO","ALB",..: 8 86 133 182 141 38 1 2 3 4 ...
.. ..$ ADM0_DIF : num [1:244] 1 0 0 1 0 0 0 0 0 0 ...
.. ..$ LEVEL : num [1:244] 2 2 2 2 2 2 2 2 2 2 ...
.. ..$ TYPE : Factor w/ 7 levels "Country","County",..: 3 6 4 5 4 6 6 6 6 6 ...
.. ..$ ADMIN : Factor w/ 253 levels "Afghanistan",..: 205 83 174 234 141 116 1 4 2 164 ...
.. ..$ ADM0_A3 : Factor w/ 253 levels "AFG","AGO","ALB",..: 204 89 137 207 145 39 1 2 3 4 ...
.. ..$ GEOU_DIF : num [1:244] 0 0 0 0 0 0 0 0 0 0 ...
.. ..$ GEOUNIT : Factor w/ 253 levels "Afghanistan",..: 205 83 174 234 141 116 1 4 2 165 ...
.. ..$ GU_A3 : Factor w/ 253 levels "AFG","AGO","ALB",..: 204 89 137 207 145 39 1 2 3 4 ...
.. ..$ SU_DIF : num [1:244] 0 0 0 0 0 0 0 0 0 0 ...
.. ..$ SUBUNIT : Factor w/ 253 levels "Afghanistan",..: 205 83 174 234 141 116 1 4 2 165 ...
.. ..$ SU_A3 : Factor w/ 253 levels "AFG","AGO","ALB",..: 204 89 137 207 145 39 1 2 3 4 ...
.. ..$ NAME : Factor w/ 250 levels "Afghanistan",..: 204 85 173 NA 144 109 1 4 2 165 ...
.. ..$ ABBREV : Factor w/ 247 levels "Afg.","Alb.",..: 203 85 173 NA 143 108 1 4 2 163 ...
.. ..$ POSTAL : Factor w/ 240 levels "A","AE","AF",..: 198 82 168 NA 138 33 3 5 4 2 ...
.. ..$ NAME_FORMA : Factor w/ 196 levels "Arab Republic of Egypt",..: NA NA NA NA 114 NA 30 55 54 NA ...
.. ..$ TERR_ : Factor w/ 15 levels "Commonwealth of U.S.A.",..: 8 NA 3 NA NA NA NA NA NA NA ...
.. ..$ NAME_SORT : Factor w/ 253 levels "Afghanistan",..: 204 88 174 207 143 40 1 4 2 165 ...
.. ..$ MAP_COLOR : num [1:244] 7 11 4 0 2 8 7 1 6 3 ...
.. ..$ POP_EST : num [1:244] 4000 1804838 -99 6000 3500000 ...
.. ..$ GDP_MD_EST : num [1:244] 0 5352 900 0 -99 ...
.. ..$ FIPS_10_ : num [1:244] -99 0 -99 -99 -99 -99 0 0 0 0 ...
.. ..$ ISO_A2 : Factor w/ 237 levels "-99","AE","AF",..: 1 1 1 1 1 1 3 6 4 2 ...
.. ..$ ISO_A3 : Factor w/ 238 levels "-99","AFG","AGO",..: 1 1 1 1 1 1 2 3 4 5 ...
.. ..$ ISO_N3 : num [1:244] -99 -99 -99 -99 -99 -99 4 24 8 784 ...
.. ..$ ISO2 : Factor w/ 222 levels "AD","AE","AF",..: NA NA NA NA NA NA 3 9 6 2 ...
.. ..$ Name : Factor w/ 232 levels "Afghanistan",..: NA NA NA NA NA NA 1 6 2 215 ...
.. ..$ FIPS : Factor w/ 222 levels "AA","AC","AE",..: NA NA NA NA NA NA 4 10 7 3 ...
..@ polygons :List of 243source
http://www.naturalearthdata.com/downloads/110m-cultural-vectors/110m-admin-0-countries/