Interval.md

@@ -23,4 +23,16 @@ The column is automatically identified and the value is turned into `ActiveSuppo
 ```ruby
 # Shows when you'll be finishing the course
 course.duration.from_now
+```
+
+The value can be set in different manners:
+```ruby
+course.duration = 1.year                 # A new instance of ActiveSupport::Duration
+course.duration = [1, 2, 3, 4, 5, 6]     # A list of values for the given order Y-M-D H:M:S
+course.duration = [1, 0, 0]              # The list uses the right-most available positions, so this is H:M:S
+course.duration = {days: 1, hours: 6}    # You can use complex hash notation
+course.duration = 'P1Y2M3DT4H5M6S'       # It accepts ISO 8601 format, so form fields can cast to this type
+
+course.duration = 259200
+course.duration.parts.to_h == {days: 3}  # It also converts any set value to the correct separated duration
 ```
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