Free Trial Duration (1 month or 30 days?)

In Apple's documentation here you can see Apple offer a 30-day introductory offer - https://developer.apple.com/app-store/subscriptions/


"for example, a 30-day trial for a subscription with a standard renewal price of $4.99 per month"


However, in iTunes connect there is no option for a 30-day introductory offer in the drop down (when setting it up) only "1 Month" is available. As our service exists across mutliple platforms (web, amazon, google) there can be different interpretations of what 1 month can be (calendar month, 31 days ....)


Does anyone have any other validation on this from the Apple side?


Thank-you