Identifier of the authority that defined the abbreviation (for 
               example, nlm-ta
 for an NLM title abbreviation, 
               publisher
 for a publisher-specific abbreviation).
            
| Value | Meaning | 
|---|---|
| Text, numbers, or special characters | A name, acronym, or descriptive word naming the authority 
                                 responsible for the abbreviation, for example, publisher, meaning that the publisher of the article assigned the abbreviation. |