Role based access control policies [RBACPs] describe the access control permissions to access the resources in multi-user information system(s) of an organization. Consequence to various changes in existing IT infrastructure, predefined RBAC polices of the organization may evolve with respect to its roles, permissions and resources sets. This work provides an insight to model these evolutions - in specific to permissions. Feature - a Design level abstraction is identified with an inherent capability to model RBACP permissions and handle their evolutions provided it is ameliorated with certain enhancements. Thus, this work defines: 1. FORBID Feature - to model the permissions and their evolutions unambiguously 2. FORBID Process a. to define FORBID features, b. to construct FORBID model c. To effect permission evolutions as FORBID feature and FORBID model evolutions systematically. 3. A FORBID Feature Management System - to archive the consistent FORBID features and enable to design valid RBACP permissions & handle their evolutions consistently.