Knowing the difference can keep you out of survey trouble. Question: Your audit of a start of care assessment shows a manifestation code listed as the primary diagnosis in M0230 without the accompanying etiology code that coding guidelines require. Which kind of error is this? A. A technical coding error that the agency's coding expert can correct without discussing it with the assessing clinician. B. A substantive coding error requiring the coder to consult with the assessing clinician and get her consent before making the change. Answer: B. This is not a technical correction, the Centers for Medicare & Medicaid Services says. If the assessing clinician left out the manifestation code that coding guidelines require, correcting that error means you have to add a diagnosis. "If any diagnosis is being added, in this case the manifestation coding requirements, the assessing clinician must be contacted and agree," CMS explains in Question 14 of the July 2006 OASIS Q&As. Once the assessing clinician agrees, agency policy will designate who makes the change and how, CMS adds. Note: CMS' July 2006 Q&As are at http://www.oasiscertificate.org, in the resources section.