This code system http://hl7.org/fhir/v3/SubstitutionCondition defines the following codes:

LvlCodeDisplayDefinitionnotSelectable
1_ConditionalConditionalSome conditions may be attached to an allowable substitution. An allowable substitution is based on a match to any other attributes that may be specified.True
2  CONFIRMConfirm firstConfirmation with Contact Person prior to making any substitutions has or will occur.
2  NOTIFYNotify firstNotification to the Contact Person, prior to substitution and through normal institutional procedures, has or will be made.
1NOSUBNo substitutionSubstitution is not permitted.
1UNCONDUnconditionalNo conditions are required.

Properties

CodeURLDescriptionType
notSelectablehttp://hl7.org/fhir/concept-properties#notSelectableIndicates that the code is abstract - only intended to be used as a selector for other conceptsBoolean