This paper evaluates the security specification techniques that employ Role Based Access Control (RBAC) variants. RBAC offers a special kind of access control mechanism based on the use of roles to grant permissions. Its variants include role hierarchy and separation of duty (SoD) constraints. The overall management of a RBAC supported system is made through its administrative, review and supporting system functions. In this paper, a summary of semi-formal and formal techniques employing RBAC is provided along with their benefits and limitations. Here, semi-formal techniques refer to UML+OCL while formal ones are based on Alloy. This paper may guide through the process of selecting an appropriate technique to specify security rules. This is done by analyzing the degree of coverage of RBAC including some extensions like SoD and role hierarchy. We also investigate the use of validation and verification tools in these techniques. We find that formal techniques are more amenable to automated analysis as compared to semi-formal ones. Semi-formal techniques are rich in specifying RBAC variants but have prototypic tools. Session based dynamic aspects of RBAC have been partly covered in both techniques.