SSL_TLSEXT_HB_DONT_RECV_REQUESTS

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
version(!OPENSSL_NO_TLSEXT && !OPENSSL_NO_HEARTBEATS)
extern (C) nothrow
enum SSL_TLSEXT_HB_DONT_RECV_REQUESTS = 0x04;

Meta