+.SS filter
+.PP
+The SVr4 documentation describes the action of \fBfilter\fR only in the vaguest
+terms.
+The description here is adapted from the XSI Curses standard (which
+erroneously fails to describe the disabling of \fBcuu\fR).
+.SS keyname
+.PP
+The \fBkeyname\fP function may return the names of user-defined
+string capabilities which are defined in the terminfo entry via the \fB\-x\fP
+option of \fB@TIC@\fP.
+This implementation automatically assigns at run-time keycodes to
+user-defined strings which begin with "k".
+The keycodes start at KEY_MAX, but are not guaranteed to be
+the same value for different runs because user-defined codes are
+merged from all terminal descriptions which have been loaded.
+The \fBuse_extended_names\fP(3X) function controls whether this data is
+loaded when the terminal description is read by the library.
+.SS nofilter/use_tioctl
+.PP
+The \fBnofilter\fP and \fBuse_tioctl\fP routines are specific to \fBncurses\fP.
+They were not supported on Version 7, BSD or System V implementations.
+It is recommended that any code depending on \fBncurses\fP extensions
+be conditioned using NCURSES_VERSION.
+.SS putwin/getwin
+.PP
+The \fBputwin\fP and \fBgetwin\fP functions have several issues with
+portability:
+.bP
+The files written and read by these functions
+use an implementation-specific format.
+Although the format is an obvious target for standardization,
+it has been overlooked.
+.IP
+Interestingly enough, according to the copyright dates in Solaris source,
+the functions (along with \fBscr_init\fP, etc.) originated with
+the University of California, Berkeley (in 1982)
+and were later (in 1988) incorporated into SVr4.
+Oddly, there are no such functions in the 4.3BSD curses sources.
+.bP
+Most implementations simply dump the binary \fBWINDOW\fP structure to the file.
+These include SVr4 curses, NetBSD and PDCurses,
+as well as older \fBncurses\fP versions.
+This implementation
+(as well as the X/Open variant of Solaris curses, dated 1995)
+uses textual dumps.
+.IP
+The implementations which use binary dumps use block-I/O
+(the \fBfwrite\fP and \fBfread\fP functions).
+Those that use textual dumps use buffered-I/O.
+A few applications may happen to write extra data in the file using
+these functions.
+Doing that can run into problems mixing block- and buffered-I/O.
+This implementation reduces the problem on writes by flushing the output.
+However, reading from a file written using mixed schemes may not be successful.
+.SS unctrl/wunctrl
+.PP