String that specifies the data type of the array to make.
      Valid strings are @float@, @double@, @long@ or @any@.
      These correspond respectively to the C types long (32 bit signed),
      float (IEEE 32-bit), double (IEEE 64-bit) and untyped. The untyped array
      may hold a heterogeneous collection of any Virtuoso data types,
      including other arrays. The initial content of the array is undefined.
      