Need more info on t.co and character count


#1

On the t.co Link Wrapper FAQ, it says:

“If you are not using the opt-in features, only links shorter in length than a t.co URL will be wrapped by t.co. All links t.co-length or longer should be considered as t.co’s maximum length. For example, if help/configuration reports 20 characters as the maximum length, and a user posts a link that is 125 characters long, it should be considered as 20 characters long instead. If they post a link that is 18 characters long, it’s still only 18 characters long.”

I am trying to post a link that is below the max length and I am still being counted at the max length. What is meant by “opt-in features” in this scenario and how can I ensure that links that are submitted below the max length are only treated with their true count?