- The last six characters of TEMPLATE before <suffix> must be "XXXXXX";
- they are replaced with a string that makes the filename unique.
+@var{suffix_len} tells us how long @var{suffix} is (it can be zero
+length). The last six characters of @var{template} before @var{suffix}
+must be @samp{XXXXXX}; they are replaced with a string that makes the
+filename unique. Returns a file descriptor open on the file for
+reading and writing.
+
+@end deftypefn
+
+*/