deferred class DURATION General cluster: time description: "Temporal intervals" Ancestors GROUP_ELEMENT* PART_COMPARABLE* Queries infix "+" (other: [like Current] DURATION): [like Current] DURATION infix "-" (other: [like Current] DURATION): [like Current] DURATION infix "<" (other: [like Current] DURATION): BOOLEAN infix "<=" (other: [like Current] DURATION): BOOLEAN infix ">" (other: [like Current] DURATION): BOOLEAN infix ">=" (other: [like Current] DURATION): BOOLEAN is_negative: BOOLEAN is_positive: BOOLEAN is_zero: BOOLEAN prefix "+": [like Current] DURATION prefix "-": [like Current] DURATION zero: [like Current] DURATION Constraints sign correctness