This activity covers the format of digital signatures, as well as procedures and policies for creation and validation. TC ESI also covers policy, security and technical requirements for trust service providers (TSP) such as certification authorities, time-stamping authorities, TSP providing remote signature creation or validation functions, registered e-delivery providers, and long-term data preservation providers. We address Trusted Lists that enhance the confidence of parties relying on certificates or other services related to digital signatures by indicating whether a given TSP was operating under the approval of any recognized scheme.