What is a Unique Identifier (UID) and why is it necessary for each record?

Question

What is a Unique Identifier (UID) and why is it necessary that each record in the Summon Index have one?

Answer

A unique identifier (UID) is an identifier that marks that particular record as unique from every other record. It allows the record to be referenced in the Summon Index without confusion or unintentional overwriting from other records. 

Examples

• If two records in the same package both have an identifier of 000001, the system cannot distinguish between the two articles and will not view them as unique from one another. It is random which article will take precedence and load into the Index, effectively overwriting the other record, dropping it from the Index and making it unavailable to patrons. 
• There are many standardized instances of Unique Identifiers available already, such as DOI or PMID, although internal identifiers are valid, too, as long as they are unique. For example, the markup distinguishes each record as unique with a series of numbers: ex.<recordID>9834556</recordID>
• The UID also allows for updates or deletes to overwrite the correct record. Without a unique identifier, the updated record or the delete request cannot match to the intended record in the index. 

Unique document identifier

• DOI ("Digital Object Identifier")
• Gale Doc ID
• EBSCO Accession Number
• PubMed's PMID

• Article last edited: 22-Feb-2017