[{ "id": "world", "name": "world", "srs": "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs", "Datasource": { "file": "http://tilemill-data.s3.amazonaws.com/world_borders_merc.zip", "type": "shape", "estimate_extent": "true", "id": "world" } }, { "id": "countries", "name": "countries", "srs": "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs", "class": "countries", "Datasource": { "file": "http://tilemill-data.s3.amazonaws.com/world_borders.zip", "type": "shape", "estimate_extent": "id", "id": "countries" } }]