This draft does not raise any issues specific to the ART area. The use of non UTF symbolic names is appropriate for this use case so I do not see any issues with strings. I view printable ascii as fairly well defined but if you want to be clearer, you could say 0x20 to 0x7E. As an outside reader not involved with the spring WG, this draft was relatively easy to understand. I do not see any problems with publication.