Replace Recommended rules for case 4 pattern with this:

Recommended rules for case 4 pattern:
Note that the code element actually determines the semantics of the Observation resource. A value of 30/min, for instance, means very different things depending on whether the code is for pulse rate or respiration rate. Similarly, the term "tenderness" is useless without the context of the "abdominal exam" code. For this reason, we discourage the use of the "one-code", pattern: no matter which element is chosen, the relationship of the term to the patient may not be clear.

More specifically, assessments of the presence of a phenomenon should explicitly assert presence. This is for two reasons. First, this pattern preserves the two-element information pattern used in all other cases. Second, the one-element pattern does not support representation of pertinent negatives. The absence of a record of abdominal tenderness may represent absence of tenderness, but it may also represent an absence of information. Only by maintaining consistency in the assertion of presence and absence can the cases of presence, absence, and indeterminacy be made explicitly and reliably distinct. Which is to say, eschew pattern 4 for pattern 3, and put the "this finding is present" stipulation in value, not dataAbsentReason.