SBVR_ — clarification needed for 'reference scheme uses characteristic'

The discussion of 'reference scheme uses characteristic' on page 29 or 30 in section 8.4 is poorly worded and confusing:

• The diagram and text can be misread to imply that a reference scheme can be based solely on a characteristic. Perhaps there should be a necessity
  rule along the lines of "Each reference scheme simply uses at least one role or each reference scheme extensionally uses at least one role" and
  a possibility rule such as "Each reference scheme uses some characteristics".

• The Note is garbled, where it says "Using a characteristic in a reference scheme is equivalent to using a binary fact type with a Boolean role whose
  value is true then ...." This could be misread as saying that using a characteristic is equivalent to using a binary fact type, which of course is not true.
  Or one could parse this as "a binary fact type with a Boolean role" which also doesn't make sense. What's really meant is something like "... using a
  binary fact type in conjunction with a Boolean role ...."

• The last sentence of the Note doesn't make sense. It says "But business vocabularies don't tend to define binary relationships to Booleans, but, rather,
  they define characteristics." Booleans are unary (not binary) fact types. So what would it mean to "define binary relationships to Booleans?

Clarify the notes under "reference scheme" and "reference scheme uses characteristic". Add examples of references schemes and of references based on them.