This case-sensitive code system http://terminology.hl7.org/CodeSystem/allergyintolerance-verification defines the following codes in an undefined hierarchy:
Lvl
Code
Display
Definition
1
unconfirmed
Unconfirmed
The propensity for a reaction to the identified substance has not been objectively verified.
2
presumed
Presumed
The available clinical information supports a high liklihood of the propensity for a reaction to the identified substance.
1
confirmed
Confirmed
The propensity for a reaction to the identified substance has been objectively verified (which may include clinical evidence by testing, rechallenge, or observation).
1
refuted
Refuted
A propensity for a reaction to the identified substance has been disputed or disproven with a sufficient level of clinical certainty to justify invalidating the assertion. This might or might not include testing or rechallenge.
1
entered-in-error
Entered in Error
The statement was entered in error and is not valid.