In the last episode (Dec 13), Marcus Comstedt (ACROSS) (Hail Ilpalazzo!) @ Pike (-) developers forum said:
The question was whether it would be most useful to give an error, or to silently insert the required whitespace.
Depends, I guess, on whether you want the encoding to be reversible or not. The array notation lets you generate input that cannot legally be encoded, so if you bend a bit during encoding, you end up with something that when decoded, does not match your original array. Since we're really only talking about email headers here it probably doesn't matter one way or another.