# text.div
This case-sensitive code system http://hl7.org/fhir/reaction-event-certainty defines the following codes:

Code | Display | Definition
unlikely | Unlikely | There is a low level of clinical certainty that the reaction was caused by the identified substance.
likely | Likely | There is a high level of clinical certainty that the reaction was caused by the identified substance.
confirmed | Confirmed | There is a very high level of clinical certainty that the reaction was due to the identified substance, which may include clinical evidence by testing or rechallenge.
unknown | Unknown | The clinical certainty that the reaction was caused by the identified substance is unknown. It is an explicit assertion that certainty is not known.

# concept[].definition
There is a low level of clinical certainty that the reaction was caused by the identified substance.

# concept[].definition
There is a high level of clinical certainty that the reaction was caused by the identified substance.

# concept[].definition
There is a very high level of clinical certainty that the reaction was due to the identified substance, which may include clinical evidence by testing or rechallenge.

# concept[].definition
The clinical certainty that the reaction was caused by the identified substance is unknown.  It is an explicit assertion that certainty is not known.