This INTEGER (group1, group2, ... group5) is described as identifying the Diffie-Hellman group used for the IKE Crypto Map when one of its PFS features is enabled, referenced here at the policy level. An admin sets a stronger group on the shared policy to raise the cryptographic strength of phase-2 rekeys for every crypto map that uses this policy. For example, an admin upgrading a whole fleet of tunnels' PFS strength at once would change this policy's group from group2 to group5 rather than editing each crypto map individually.