As part of this, I noticed a problem when updating the Rust
implementation. With the BF..84 design for annotations, if you are
wanting to skip annotations—for example, if you're parsing
incrementally, SAX-style, ignoring annotations—then with any
parenthesised form you have to remember to check for and skip something
after reading a term. This is awkward, so I want to revisit the design
of annotations and go back to the prefix-form (85..) of the
current-mainline design.
Tony Garnock-Jones