[NTG-context] define an incremental personal bullet of item

Dear all, I'd like to use "circled number 1", "circled number 2", ... as bullets of itemized block. There is an explanation how to define a personal bullet in the manual. For each \item the same bullet is used. But I want bullets automatically changed to the next character in unicode table. (For example, the command "\startitemize[n]" displays next number as a bullet when the command "\item" is issued. ) Is there a way to do that? Thank you. Best regards, Dalyoung