@deftypefun {int} {gnutls_x509_crl_iter_crt_serial} (gnutls_x509_crl_t @var{crl}, gnutls_x509_crl_iter_t * @var{iter}, unsigned char * @var{serial}, size_t * @var{serial_size}, time_t * @var{t})
@var{crl}: should contain a @code{gnutls_x509_crl_t}  type

@var{iter}: A pointer to an iterator (initially the iterator should be @code{NULL} )

@var{serial}: where the serial number will be copied

@var{serial_size}: initially holds the size of serial

@var{t}: if non null, will hold the time this certificate was revoked

This function performs the same as @code{gnutls_x509_crl_get_crt_serial()} ,
but reads sequentially and keeps state in the iterator 
between calls. That allows it to provide better performance in sequences 
with many elements (50000+).

When past the last element is accessed @code{GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE} 
is returned and the iterator is reset.

After use, the iterator must be deinitialized using @code{gnutls_x509_crl_iter_deinit()} .

@strong{Returns:} On success, @code{GNUTLS_E_SUCCESS}  (0) is returned, otherwise a
negative error value.
@end deftypefun