@subheading asn1_check_version
@anchor{asn1_check_version}
@deftypefun {const char *} {asn1_check_version} (const char * @var{req_version})
@var{req_version}: Required version number, or @code{NULL} .

Check that the version of the library is at minimum the
requested one and return the version string; return @code{NULL}  if the
condition is not satisfied.  If a @code{NULL}  is passed to this function,
no check is done, but the version string is simply returned.

See @code{ASN1_VERSION}  for a suitable  @code{req_version} string.

@strong{Returns:} Version string of run-time library, or @code{NULL}  if the
run-time library does not meet the required version number.
@end deftypefun

