openssl/core.h - OpenSSL Core types
 #include <openssl/core.h>
The <openssl/core.h> header defines a number of public types that
  are used to communicate between the OpenSSL libraries and implementation
  providers. These types are designed to minimise the need for intimate
  knowledge of internal structures between the OpenSSL libraries and the
  providers.
The types are:
  - OSSL_DISPATCH(3)
- OSSL_ITEM(3)
- OSSL_ALGORITHM(3)
- OSSL_PARAM(3)
- OSSL_CALLBACK(3)
- OSSL_PASSPHRASE_CALLBACK(3)
openssl-core_dispatch.h(7)
The types described here were added in OpenSSL 3.0.
Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.Licensed under the Apache License 2.0 (the "License").
    You may not use this file except in compliance with the License. You can
    obtain a copy in the file LICENSE in the source distribution or at
    <https://www.openssl.org/source/license.html>.