1) Adaptable 2) Capable of being regulated 3) Changeable 4) Not set 5) Not set in stone 
• (a.) Capable of being adjusted.
Ad·just'a·ble adjective Capable of being adjusted. 
[adj] - capable of being changed so as to match or fit 2. [adj] - capable of being regulated
adjective capable of being regulated; `adjustable interest rates`
capable of being adjusted: adjustable seat belts. · (of loans, mortgages, etc.) having a flexible rate, as one based on money market interest rates or on the rate of inflation or cost of living. · (esp. of life insurance) having flexible premiums and coverage, based on the insuree's current needs and ability to pay.