Hi Craig,
We use Annotation Comment 48767-8 for such a comment. The definition reads “This is an observation code indicating that a particular observation represents a free text annotation comment that can be appended to some other observation such as a lab result.”
We like this better than the Service Comment series, because they can be used for a different intent in the receiving system than in your sending system, and the note could get misinterpreted. Both sides using 48767-8 would understand that this is additional information.
Hope this helps,
Pam Banning, pdbanning@mmm.com