Ada Programming/Libraries/Ada.Calendar.Arithmetic

is a unit of the Predefined Language Environment since Ada 2005.

Specification
Day_Count 366 1  Year_Number  Year_Number 366 1  Year_Number  Year_Number Leap_Seconds_Count Integer  2047  2047 Difference Left              Time Right             Time Days             Day_Count Seconds          Duration Leap_Seconds     Leap_Seconds_Count "" Left   Time Right  Day_Count Time "" Left   Day_Count Right  Time Time "" Left   Time Right  Day_Count Time "" Left   Time Right  Time Day_Count AdaCalendarArithmetic

Wikibook

 * Ada Programming/Libraries/Ada