+.SS Legacy functions
+.PP
+X/Open notes that \fBvidattr\fR and \fBvidputs\fR may be macros.
+.PP
+The function \fBsetterm\fR is not described by X/Open and must
+be considered non-portable.
+All other functions are as described by X/Open.
+.SS Legacy data
+.PP
+\fBsetupterm\fP copies the terminal name to the array \fBttytype\fP.
+This is not part of X/Open Curses, but is assumed by some applications.
+.PP
+Other implementions may not declare the capability name arrays.
+Some provide them without declaring them.
+X/Open does not specify them.
+.PP
+Extended terminal capability names, e.g., as defined by \fB@TIC@\ \-x\fP,
+are not stored in the arrays described here.
+.SS Output buffering
+.PP
+Older versions of \fBncurses\fP assumed that the file descriptor passed to
+\fBsetupterm\fP from \fBinitscr\fP or \fBnewterm\fP uses buffered I/O,
+and would write to the corresponding stream.
+In addition to the limitation that the terminal was left in block-buffered
+mode on exit (like System V curses),
+it was problematic because \fBncurses\fP
+did not allow a reliable way to cleanup on receiving SIGTSTP.
+.PP
+The current version (ncurses6)
+uses output buffers managed directly by \fBncurses\fP.
+Some of the low-level functions described in this manual page write
+to the standard output.
+They are not signal-safe.
+The high-level functions in \fBncurses\fP use
+alternate versions of these functions
+using the more reliable buffering scheme.
+.SS Function prototypes
+.PP
+The X/Open Curses prototypes are based on the SVr4 curses header declarations,
+which were defined at the same time the C language was first standardized in
+the late 1980s.
+.bP
+X/Open Curses uses \fBconst\fP less effectively than a later design might,
+in some cases applying it needlessly to values are already constant,
+and in most cases overlooking parameters which normally would use \fBconst\fP.
+Using constant parameters for functions which do not use \fBconst\fP
+may prevent the program from compiling.
+On the other hand, \fIwritable strings\fP are an obsolescent feature.
+.IP
+As an extension, this implementation can be configured to change the
+function prototypes to use the \fBconst\fP keyword.
+The ncurses ABI 6 enables this feature by default.
+.bP
+X/Open Curses prototypes \fBtparm\fR with a fixed number of parameters,
+rather than a variable argument list.
+.IP
+This implementation uses a variable argument list, but can be
+configured to use the fixed-parameter list.
+Portable applications should provide 9 parameters after the format;
+zeroes are fine for this purpose.
+.IP
+In response to review comments by Thomas E. Dickey,
+X/Open Curses Issue 7 proposed the \fBtiparm\fP function in mid-2009.
+.SS Special TERM treatment
+.PP
+If configured to use the terminal-driver,
+e.g., for the MinGW port,
+.bP
+\fBsetupterm\fP interprets a missing/empty TERM variable as the
+special value \*(``unknown\*(''.
+.bP
+\fBsetupterm\fP allows explicit use of the
+the windows console driver by checking if $TERM is set to
+\*(``#win32con\*('' or an abbreviation of that string.
+.SS Other portability issues
+.PP
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