On Thu, Mar 10, 2016 at 12:18:34AM +0000, Mark Andrews via RT wrote:
> People also expect nameservers to reject garbage in records which is
> what named and dig are doing when they can.

See my previous statement about obvious correctness.  However, since
other implementors are likely to follow the RFC and allow nonalphanumeric
characters, and this will affect interoperability, I think Robert's
suggestion of allowing such records in wire-format but switching to
unknown-type format when rendering them to text is a pretty good one.