sortDirection
Specifies ascending or descending order in a sort clause. asc and ascending are equivalent; desc and descending are equivalent. Ascending is the default when no direction is given.
Examples
Ascending sort (short form)
from [Observation] O sort by O.effective asc
Descending sort (long form)
from [Encounter] E sort by E.period.start descending
Sort entire list descending
from [Observation] O sort desc
EBNF
sortDirection : 'asc' | 'ascending' | 'desc' | 'descending' ;