The correct options are
A It acts as a boundary between two calender dates.
C The IDL has no legal international status in the world.
D It is not a straight line and has a zig-zag pattern.
The International Date Line (IDL) acts as a 'line of demarcation" between two consecutive calender dates. It was established in the year 1884. It runs through the middle of the Pacific Ocean and roughly follows the 180° longitude. It is not a straight line and has a zig-zag pattern. The IDL has no legal international status. Thus, countries are free to choose any date as the IDL.