From Steve Huston's comments:

Part 3, section 2.10: Refers to allowed symbolic keys as starting with
both "x=" and "x-opt-" - which is right?
Also, quoted terms use close quotes at start and end; change the start to
open quotes (`` in latex, I believe)

RS: Rephrase language to be positive, e.g., "Keys beginning with "x-opt-" MUST be ignored if not understood. All other keys MUST result in a blah error if not understood."