# File lib/geo_ruby/simple_features/geometry.rb, line 47
      def as_ewkb(allow_srid=true,allow_z=true,allow_m=true)
        ewkb="";
       
        ewkb << 1.chr #little_endian by default

        
        type= binary_geometry_type
        if @with_z and allow_z
          type = type | Z_MASK
        end
        if @with_m and allow_m
          type = type | M_MASK
        end
        if allow_srid
          type = type | SRID_MASK
          ewkb << [type,@srid].pack("VV")
        else
          ewkb << [type].pack("V")
        end
        
        ewkb << binary_representation(allow_z,allow_m)
      end