These values are currently used in gdalraster
when a nodata value is
needed but has not been specified:
list("Byte" = 255, "Int8" = -128,
"UInt16" = 65535, "Int16" = -32767,
"UInt32" = 4294967293, "Int32" = -2147483647,
"Float32" = -99999.0, "Float64" = -99999.0)