@deftypefun {int} {gnutls_x509_crt_set_version} (gnutls_x509_crt_t @var{crt}, unsigned int @var{version}) @var{crt}: a certificate of type @code{gnutls_x509_crt_t} @var{version}: holds the version number. For X.509v1 certificates must be 1. This function will set the version of the certificate. This must be one for X.509 version 1, and so on. Plain certificates without extensions must have version set to one. To create well-formed certificates, you must specify version 3 if you use any certificate extensions. Extensions are created by functions such as @code{gnutls_x509_crt_set_subject_alt_name()} or @code{gnutls_x509_crt_set_key_usage()} . @strong{Returns:} On success, @code{GNUTLS_E_SUCCESS} (0) is returned, otherwise a negative error value. @end deftypefun