qualifier
A qualifier is an identifier used as a namespace prefix in qualified names. Qualifiers appear before a dot in qualified identifiers and named type specifiers to scope a name within a library or model namespace.
Examples
Library name as qualifier
FHIRHelpers.ToInterval
Model name as qualifier in a type specifier
parameter "Patient" FHIR.Patient
Namespace qualifier in library declaration
library org.hl7.fhir.DiabetesManagement version '1.0.0'
EBNF
qualifier : identifier ;