idx = zip.AddDirectory(id, d$[, t])
d$
in the zip archive and returns
its index. The directory will be empty and you can add files to it using
the zip.AddFile() function.
The following tags are currently recognized by the optional table argument:
Encoding:
#ZIP_FL_ENC_UTF_8:
#ZIP_FL_ENC_CP437:
(V1.2)