The rate on student loans can't change by more than 0.25% every year and is tied to an index when loan is issued

This petition is similar to my mortgage. It is tied to an index where my loan can not exceed that index by more that a fixed amount say 1.5%. Let the index be the federal funds rate assume it is 2.0% today and the loan is issued at 3.4%. The loan then has a maximum rate of 1.4% over the federal funds rate. The rate increase up or down can not exceed 0.25% per year. So if the loans interest rate today is 3.4% and the federal funds rate (or could be the 10 year treasury yield for example) increases instantaneously to 8% the loan can only increase 1% every four years. Likewise if the rate should suddenly decrease it can only go down at the same limited amount. In short this is a variable rate loan tied to an index that protects the student loan holder from catastrophic increases.