ZTreeWin uses 7-Zip's archive engine for archives, and 7-Zip's SFX module
for self-extracting ones:

  Opened, viewed and extracted: 7z, zip, rar (and rar5), tar, gz, bz2, xz,
  cab, iso, lzh, arj, wim, msi and the other formats 7-Zip reads, passwords
  included.

  Created (F5, Ctrl-F5): zip, 7z, exe (a self-extracting .7z), tar, tar.gz,
  tar.xz and tar.bz2; zip, 7z and exe can be encrypted. 7-Zip cannot create
  rar, cab, iso, lzh, arj or the other formats it only reads: those need
  their own program named in ARCHIVER.BB2 (rar.exe for rar).

  7z64.dll    7-Zip 26.04's 7z.dll (x64), unchanged, renamed for ZTW64.EXE
  7z32.dll    7-Zip 26.04's 7z.dll (x86), unchanged, renamed for ZTW.EXE
  7zCon.sfx   7-Zip 26.04's 7zCon.sfx (its console SFX module), unchanged:
              put in front of the .7z in an .exe made by Ctrl-F5, it
              unpacks the archive by itself
                https://www.7-zip.org

7-Zip is Copyright (C) 1999-2026 Igor Pavlov, and is distributed under the
GNU LGPL; the RAR decoder in 7z.dll under the GNU LGPL with the unRAR
licence restriction, and a few files under BSD licences. Its licence, with
the unRAR restriction, is in 7z-License.txt next to this file. The source
of these files is 7-Zip 26.04's source archive, at
  https://www.7-zip.org/download.html

ZTreeWin itself is not covered by that licence: it loads 7z64.dll/7z32.dll
at run time, and copies 7zCon.sfx into the archives it is asked to make
self-extracting. A self-extracting archive carries 7zCon.sfx, under the
same GNU LGPL; the files packed in it are not covered by that licence.

Without the DLLs ZTreeWin still runs; archives then need the external
programs ARCHIVER.BB2 names. Without 7zCon.sfx (or 7z.sfx), Ctrl-F5 offers
no .exe unless 7-Zip itself is installed.
