If curl was built with support for "MultiSSL", meaning that it has built-in
support for more than one TLS backend, this environment variable can be set to
the case insensitive name of the particular backend to use when curl is
-invoked. Setting a name that isn't a built-in alternative, will make curl
+invoked. Setting a name that isn't a built-in alternative will make curl
stay with the default.
+
+SSL backend names (case-insensitive): bearssl, gnutls, gskit, mbedtls,
+mesalink, nss, openssl, rustls, schannel, secure-transport, wolfssl
.IP "QLOGDIR <directory name>"
If curl was built with HTTP/3 support, setting this environment variable to a
local directory will make curl produce qlogs in that directory, using file
.IP CURL_SSL_BACKEND
When libcurl is built to support multiple SSL backends, it will select a
specific backend at first use. If no selection is done by the program using
-libcurl, this variable's selection will be used. It should be set to the full
-SSL backend name to use (case insensitive).
+libcurl, this variable's selection will be used. Setting a name that isn't a
+built-in alternative will make libcurl stay with the default.
+
+SSL backend names (case-insensitive): bearssl, gnutls, gskit, mbedtls,
+mesalink, nss, openssl, rustls, schannel, secure-transport, wolfssl
.IP HOME
When the netrc feature is used (\fICURLOPT_NETRC(3)\fP), this variable is
checked as the primary way to find the "current" home directory in which