X25(6) - phpMan

Net::DNS::RR::X25 (3pm) - DNS X25 resource record
x25 (7)              - ITU-T X.25 / ISO-8208 protocol interface.
X25519 (7ssl)        - EVP_PKEY X25519 and X448 support
X448 (7ssl)          - EVP_PKEY X25519 and X448 support