This value set has an inline code system http://hl7.org/fhir/v3/substanceAdminSubstitution, which defines the following codes:
| Lvl | Code | Display | Definition | 
| 1 | _ActSubstanceAdminSubstitutionCode | ActSubstanceAdminSubstitutionCode | Description: Substitution occurred or is permitted with another product that may potentially have different ingredients, but having the same biological and therapeutic effects. | 
| 2 | E | equivalent | Description: Substitution occurred or is permitted with another bioequivalent and therapeutically equivalent product. | 
| 3 | EC | equivalent composition | Description: Substitution occurred or is permitted with another product that is a:
 pharmaceutical alternative containing the same active ingredient but is formulated with different salt, ester
                           pharmaceutical equivalent that has the same active ingredient, strength, dosage form and route of administration
                        
                        
                           Examples:
 Pharmaceutical alternative: Erythromycin Ethylsuccinate for Erythromycin Stearate
                           
                              Pharmaceutical equivalent: Lisonpril for Zestril
 | 
| 4 | BC | brand composition | Description: Substitution occurred or is permitted between equivalent Brands but not Generics
 Examples:
 Zestril  for Prinivil
                           Coumadin for Jantoven
 | 
| 4 | G | generic composition | Description: Substitution occurred or is permitted between equivalent Generics but not Brands Examples:
 Lisnopril (Lupin Corp) for Lisnopril (Wockhardt Corp)
 | 
| 3 | TE | therapeutic alternative | Description: Substitution occurred or is permitted with another product having the same therapeutic objective and safety profile. Examples:
 ranitidine for Tagamet
 | 
| 4 | TB | therapeutic brand | Description: Substitution occurred or is permitted between therapeutically equivalent Brands but not Generics >
                           Examples:
 Zantac for Tagamet
 | 
| 4 | TG | therapeutic generic | Description: Substitution occurred or is permitted between therapeutically equivalent Generics but not Brands >
                           Examples:
 Ranitidine  for cimetidine
 | 
| 2 | F | formulary | Description: This substitution was performed or is permitted based on formulary guidelines. | 
| 2 | N | none | No substitution occurred or is permitted. |