"SFX module displays "Extract" button instead of "Install" if no Setup or Presetup commands are present in the archive comment. If you prefer "Install" button, but do not need to execute any setup programs, you can add Setup=<> command. Or if you configure SFX archive through SFX options GUI dialog, just specify <> as setup program name. SFX module does not attempt to run a program with such name, but changes the button text."
"<>" may stand for nothing/blank (worked to leave that out in an xml context where these were not acceptable).
From https://documentation.help/WinRAR/HELPSFXSetup.htm:
"SFX module displays "Extract" button instead of "Install" if no Setup or Presetup commands are present in the archive comment. If you prefer "Install" button, but do not need to execute any setup programs, you can add Setup=<> command. Or if you configure SFX archive through SFX options GUI dialog, just specify <> as setup program name. SFX module does not attempt to run a program with such name, but changes the button text."
"<>" may stand for nothing/blank (worked to leave that out in an xml context where these were not acceptable).