Optional_Optional_Search ranking (between 0 and 1)
OptionalextensionAdditional content defined by implementations
OptionalidUnique id for inter-element referencing
Optionalmodematch | include | outcome - why this is in the result set
OptionalmodifierExtensions that cannot be ignored even if unrecognized
OptionalscoreSearch ranking (between 0 and 1)
match | include | outcome - why this is in the result set