According to the BABOK® v3 guide, the purpose of a roles and permissions matrix is "to ensure coverage of activities by denoting responsibility, to identify roles, to discover missing roles, and to communicate results of a planned change."
According to the BABOK® v3 guide, the purpose of a roles and permissions matrix is "to ensure coverage of activities by denoting responsibility, to identify roles, to discover missing roles, and to communicate results of a planned change."