ring fence

noun
1
a form of protection that stops a sum of money from being spent on anything other than its intended purpose
حفاظت مالی, حفاظت بودجه, حفاظ بودجه‌ای
2
a form of protection that only allows particular people to use or know something, or only allows something to be used for a particular purpose
حفاظ اختصاصی, حریم حفاظتی, محدودیت اختصاصی
He did not say when the merger would be completed or when the ring fence would be abolished.