@subheading idn2_register_ul
@anchor{idn2_register_ul}
@deftypefun {int} {idn2_register_ul} (const char * @var{ulabel}, const char * @var{alabel}, char ** @var{insertname}, int @var{flags})
@var{ulabel}: input zero-terminated locale encoded string, or NULL.

@var{alabel}: input zero-terminated ACE encoded string (xn--), or NULL.

@var{insertname}: newly allocated output variable with name to register in DNS.

@var{flags}: optional @code{idn2_flags}  to modify behaviour.

Perform IDNA2008 register string conversion on domain label  @code{ulabel} and  @code{alabel} , as described in section 4 of RFC 5891.  Note that the
input  @code{ulabel} is assumed to be encoded in the locale's default
coding system, and will be transcoded to UTF-8 and NFC normalized
by this function.

It is recommended to supply both  @code{ulabel} and  @code{alabel} for better
error checking, but supplying just one of them will work.  Passing
in only  @code{alabel} is better than only  @code{ulabel} .  See RFC 5891 section
4 for more information.

After version 0.11:  @code{insertname} may be NULL to test conversion of  @code{src} without allocating memory.

@strong{Returns:} On successful conversion @code{IDN2_OK}  is returned, when the
given  @code{ulabel} and  @code{alabel} does not match each other
@code{IDN2_UALABEL_MISMATCH}  is returned, when either of the input
labels are too long @code{IDN2_TOO_BIG_LABEL}  is returned, when  @code{alabel} does does not appear to be a proper A-label @code{IDN2_INVALID_ALABEL} 
is returned, when  @code{ulabel} locale to UTF-8 conversion failed
@code{IDN2_ICONV_FAIL}  is returned, or another error code is returned.
@end deftypefun

