Remove obsolete lines like this:

\setindexsubitem{(in module frobnitz)}

These are no longer needed when present before any other \setindexsubitem{}
in the module section.  The indexsubitem is now set by \bimodindex and
\stmodindex.

Doc/lib/libtermios.tex

@@ -98,7 +98,6 @@ def getpass(prompt = "Password: "):
 \indexii{\POSIX{}}{I/O control}
 \indexii{tty}{I/O control}
 
-\setindexsubitem{(in module TERMIOS)}
 
 This module defines the symbolic constants required to use the
 \module{termios}\refbimodindex{termios} module (see the previous