Systems and data: validating a cluster

Is this cluster valid?

Is this cluster valid? WHO's API can tell you, and explain why.

Pass a code, or a combination

The codeinfo endpoint takes a code or a combination string. For a postcoordinated string, it returns the stem code and which axes are used with which values. WHO's own worked example has a stem, a laterality value and a specific anatomy value.

• Input · 2C25.Z&XK8G&XA9HN5 · A stem code or a code combination string.
• Output · Split · For a combination, the stem code and which axes are used with which values.

A valid code, an invalid cluster

If every individual code is valid but the combination isn't, the API returns a not found error. With flexiblemode set to true, you get the usual response, and the codes that don't match the allowed axes appear under other postcoordination.

Newer and richer

Version two point five added a describe endpoint, with more detail on combinations, including the axes used. And the postcoordination scales are exposed as FHIR value sets, so a code can be validated against an axis.

• describe · v2.5 · A describe endpoint gives more detail on a code, URI or combination, including which axes are used.
• Axes · Value sets · Postcoordination scales are exposed as FHIR ValueSets, so a code can be validated against an axis.

Check yourself

Pause and think. Every individual code is valid but the combination isn't. What does the API return? The answer: A not found error. If every individual code is valid but the combination isn't, the API returns a not found error.

• A successful response
• A not found error
• A warning with the stem code only
• The first code in the string

Keep these in mind

codeinfo explains a combination. A valid code can still make an invalid cluster. And check the API reference for the current parameters.

• codeinfo explains a combination
• A valid code can still make an invalid cluster
• Check the API reference for current parameters