What are qualified and unqualified identifiers?
A qualified identifier is one which conforms to the NCBI standard FASTA identifier (NSID) syntax outlined in Table 1. An unqualified identifier is just a bare word, lacking any indication of its database domain or name space in which it was assigned. For instance, while U38670 could represent a GenBank Accession, it might also be an uncontrolled identifier (UCID). The string gb|U38670| tells us unambiguously that the identifier is a GenBank Accession. Table 2.
